Measurement system configured to support installation of a ball and socket joint and method therefor

ABSTRACT

A system is disclosed herein for providing a kinetic assessment and preparation of a prosthetic joint comprising one or more prosthetic components. The system comprises a prosthetic component including sensors and circuitry configured to measure load, position of load on a curved surface, joint stability, range of motion, and impingement. In one embodiment, the system is for a cup and ball joint of a musculoskeletal system. The system further includes a computer having a display configured to graphical display quantitative measurement data to support rapid assimilation of the information. The kinetic assessment measures joint alignment under loading that will be similar to that of a final joint installation. The kinetic assessment can use trial or permanent prosthetic components. Furthermore, adjustments can be made to the applied load magnitude, position of load, and joint alignment by various means to fine-tune an installation.

FIELD OF THE INVENTION

The invention relates in general to medical and surgical devices andmore particularly to parameter measurement related to themusculoskeletal system.

BACKGROUND OF THE INVENTION

The musculoskeletal system of a mammal is subject to breakdown due tomany factors such as environment, genetics, diet, usage, and aging. Ajoint of the musculoskeletal system typically comprises two or morebones that move in relation to one another. Movement is enabled bymuscle tissue and tendons attached to the joint. Ligaments hold andstabilize the one or more joint bones positionally. Cartilage is a wearsurface that prevents bone-to-bone contact, distributes load, and lowersfriction.

There has been substantial growth in the repair of the humanmusculoskeletal system. In general, prosthetic orthopedic joints haveevolved over time using animal studies, empirical evidence, simulationdata, mechanical prototypes, and patient data. The tools being used fororthopedic surgery have been refined over the years but have not changedsubstantially. Thus, the basic procedure for replacement of anorthopedic joint has been standardized to meet the general needs of awide distribution of the population. Although the tools, procedure, andartificial joint meet a general need, each replacement procedure issubject to significant variation from patient to patient. The correctionof these individual variations relies on the skill of the surgeon toadapt and fit the replacement joint using the available tools to thespecific circumstance. It would be of great benefit to providequantitative measurement data in real-time to support installation ofprosthetic components or prosthetic joints.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a prosthetic shoulder joint in accordancewith an example embodiment;

FIG. 2 is an illustration of a prosthetic shoulder joint in accordancewith an example embodiment;

FIG. 3 is an illustration of a measurement device in a shoulder jointsystem in accordance with an example embodiment;

FIG. 4A is a flow diagram for a shoulder joint installation using themeasurement device of FIG. 3 in accordance with an example embodiment;

FIG. 4B is a continuation of the flow diagram from FIG. 4A for theshoulder joint installation using the measurement device of FIG. 3 inaccordance with an example embodiment;

FIG. 5 is an exploded view of the measurement device illustratingcomponents in accordance with an example embodiment;

FIG. 6 is an exploded side view of the measurement device in accordancewith an example embodiment;

FIG. 7 is an illustration of the upper housing coupled to the bottomhousing in accordance with an example embodiment;

FIG. 8 is a cross-section of the measurement device in accordance withan example embodiment;

FIG. 9 is an illustration of mechanical features of the enclosure of themeasurement device in accordance with an example embodiment;

FIG. 10 is a cross-sectional view of part of the enclosure illustratingthe sensor between the upper housing and the bottom housing inaccordance with an example embodiment;

FIG. 11 is a cross-sectional view of the measurement device illustratingthe external curved surface of the upper housing in accordance with anexample embodiment;

FIG. 12 is an illustration of a sensor snap formed in the bottom housingin accordance with an example embodiment;

FIG. 13 is a cross-sectional view of the bottom housing illustrating asolder hole in accordance with an example embodiment;

FIG. 14 is an illustration of the support structure in the bottomhousing configured to couple to the flexible interconnect in accordancewith an example embodiment;

FIG. 15 is a cross-sectional view of a portion of the upper housing, thebottom housing, and the humeral tray in accordance with an exampleembodiment;

FIG. 16 is an illustration of a housing snap on the measurement deviceto couple the upper housing to the bottom housing in accordance with anexample embodiment;

FIG. 17 is an illustration of rigid snaps extending from the bottomhousing in accordance with an example embodiment;

FIG. 18 is an illustration of the o-ring in the measurement device inaccordance with an example embodiment;

FIG. 19 is an illustration of the bottom housing with the electroniccircuitry in accordance with an example embodiment;

FIG. 20 is an illustration of the flexible interconnect in accordancewith an example embodiment;

FIG. 21 is an illustration of the measurement device in accordance withan example embodiment;

FIG. 22A is an illustration of a GUI on the display of the computer inaccordance with an example embodiment;

FIG. 22B is an illustration of the GUI indicating impingement inaccordance with an example embodiment;

FIG. 23 is an illustration of the GUI on the display coupled to thecomputer displaying sensor information related to range of motion fromthe measurement device in accordance with an example embodiment;

FIG. 24 is an illustration of an option screen in accordance with anexample embodiment;

FIG. 25 is an illustration of a range of motion (ROM) overlay on the GUI380 in accordance with an example embodiment;

FIG. 26 is an illustration of the GUI showing an impingement range ofmotion assessment in accordance with an example embodiment;

FIG. 27A is an illustration of measurement data from the measurementdevice in accordance with an example embodiment;

FIG. 27B is an illustration of the measurement device transmittingmeasurement data to the computer and displaying the measurement data onthe display in accordance with an example embodiment;

FIG. 28 illustrates a cross-sectional view of the external curvedsurface of the measurement device as shown in FIG. 21 in accordance withan example embodiment;

FIG. 29A is an illustration of a spherical coordinate system forcalculating force and position in accordance with an example embodiment;

FIG. 29B is an example of force and position calculations related tosensor location in accordance with an example embodiment;

FIG. 30 is a diagram showing a force magnitude calculation frommeasurement data from the sensors in accordance with an exampleembodiment;

FIG. 31 is a diagramming showing a position of applied load calculationon the external curved surface of the measurement device usingmeasurement data from the sensors in accordance with an exampleembodiment;

FIG. 32 is a block diagram of the electronic circuitry in themeasurement device in accordance with an example embodiment;

FIG. 33 is a block diagram of the system or computer in accordance withan example embodiment;

FIG. 34 is an illustration of a communication network for measurementand reporting in accordance with an exemplary embodiment;

FIG. 35 is a diagram of a robot supporting installation of a shoulderjoint in accordance with an example embodiment;

FIG. 36 is a measurement device in accordance with an exampleembodiment;

FIG. 37A is a superior view of the measurement device in accordance withan example embodiment;

FIG. 37B is a view of the measurement device illustrating the externalcurved surface in accordance with an example embodiment;

FIG. 37C is a side view of the measurement device in accordance with anexample embodiment;

FIG. 37D is an anterior view of the measurement device illustrating anunder-cut formed in a shim in accordance with an example embodiment;

FIG. 38 is an exploded view of the measurement device in accordance withan example embodiment;

FIG. 39 is a view of a cavity of a bottom housing of the measurementdevice in accordance with an example embodiment;

FIG. 40 is a cross-sectional view of the measurement device inaccordance with an example embodiment;

FIG. 41A illustrates the measurement device with first shim inaccordance with an example embodiment;

FIG. 41B illustrates the measurement device with a second shim inaccordance with an example embodiment;

FIG. 42 is a cross-sectional view of the external curved surface of theupper housing that is modified to direct loading to predetermined areasof the external curved surface in accordance with an example embodiment;

FIG. 43 is a block diagram of loading the measurement device inaccordance with an example embodiment; and

FIG. 44 is an illustration of the measurement device illustratingdifferent regions of the external curved surface of the upper housing inaccordance with an example embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

The following description of embodiment(s) is merely illustrative innature and is in no way intended to limit the invention, itsapplication, or uses.

For simplicity and clarity of the illustration(s), elements in thefigures are not necessarily to scale, are only schematic and arenon-limiting, and the same reference numbers in different figures denotethe same elements, unless stated otherwise. Additionally, descriptionsand details of well-known steps and elements are omitted for simplicityof the description. Notice that once an item is defined in one figure,it may not be discussed or further defined in the following figures.

The terms “first”, “second”, “third” and the like in the Claims or/andin the Detailed Description are used for distinguishing between similarelements and not necessarily for describing a sequence, eithertemporally, spatially, in ranking or in any other manner. It is to beunderstood that the terms so used are interchangeable under appropriatecircumstances and that the embodiments described herein are capable ofoperation in other sequences than described or illustrated herein.

Processes, techniques, apparatus, and materials as known by one ofordinary skill in the art may not be discussed in detail but areintended to be part of the enabling description where appropriate.

The orientation of the x, y, and z-axes of rectangular Cartesiancoordinates is assumed to be such that the x and y axes define a planeat a given location, and the z-axis is normal to the x-y plane. The axesof rotations about the Cartesian axes of the device are defined as yaw,pitch and roll. With the orientation of the Cartesian coordinatesdefined in this paragraph, the yaw axis of rotation is the z-axisthrough body of the device. Pitch changes the orientation of alongitudinal axis of the device. Roll is rotation about the longitudinalaxis of the device.

The orientation of the X, Y, Z axes of rectangular Cartesian coordinatesis selected to facilitate graphical display on computer screens havingthe orientation that the user will be able to relate to most easily.Therefore the image of the device moves upward on the computer displaywhenever the device itself moves upward for example away from thesurface of the earth. The same applies to movements to the left orright.

Although inertial sensors are provided as enabling examples in thedescription of embodiments, any tracking device (e.g., a GPS chip,acoustical ranging, accelerometer, magnetometer, gyroscope,inclinometers, MEMs devices) can be used within the scope of theembodiments described.

At least one embodiment is directed to a kinetic orthopedic measurementsystem to aid a surgeon in determining real time alignment, range ofmotion, loading, impingement, and contact point of orthopedic implants.Although the system is generic to any orthopedic surgery (e.g., spinal,shoulder, knee, hip, ankle, wrist, finger, toe, bone, musculoskeletal,etc.) the following examples deal with shoulder surgery as anon-limiting example of an embodiment of the invention.

The non-limiting embodiment described herein is related to quantitativemeasurement based orthopedic surgery and referred to herein as thekinetic system. The kinetic system includes a sensor system thatprovides quantitative measurement data and feedback that can be providedvisually, audibly, or haptically to a surgeon or surgical team. Thekinetic system provides the surgeon real-time dynamic data regardingforce, pressure, or loading on the shoulder joint, contact andcongruency through a full range of motion, and information regardingimpingement.

In general, kinetics is the study of the effect of forces upon themotion of a body or system of bodies. Disclosed herein is a system forkinetic assessment of the musculoskeletal system. The kinetic system canbe for the installation of prosthetic components or for monitoring andassessment of permanently installed components to the musculoskeletalsystem. For example, installation of a prosthetic component can requireone or more bone surface to be prepared to receive a device orcomponent. The kinetic system is designed to take quantitativemeasurements of at least the load, position of load, or alignment withthe forces being applied to the joint similar to that of a final jointinstallation. The sensored measurement components are designed to allowligaments, tissue, and bone to be in place while the quantitativemeasurement data is taken. This is significant because the bone cutstake into account the kinetic forces where a kinematic assessment andsubsequent bone cuts could be substantial changed from an alignment,load, and position of load once the joint is reassembled.

A prosthetic joint installation can benefit from quantitativemeasurement data in conjunction with subjective feedback of theprosthetic joint to the surgeon. The quantitative measurements can beused to determine adjustments to bone, prosthetic components, or tissueprior to final installation. Permanent sensors can also be housed infinal prosthetic components to provide periodic data related to thestatus of the implant. Data collected intra-operatively and long termcan be used to determine parameter ranges for surgical installation andto improve future prosthetic components. The physical parameter orparameters of interest can include, but are not limited to, measurementof alignment, load, force, pressure, position, displacement, density,viscosity, pH, spurious accelerations, color, movement, particulatematter, structural integrity, and localized temperature. Often, severalmeasured parameters are used to make a quantitative assessment. Agraphical user interface can support assimilation of measurement data.Parameters can be evaluated relative to orientation, alignment,direction, displacement, or position as well as movement, rotation, oracceleration along an axis or combination of axes by wireless sensingmodules or devices positioned on or within a body, instrument,appliance, vehicle, equipment, or other physical system.

While the specification concludes with claims defining the features ofthe invention that are regarded as novel, it is believed that theinvention will be better understood from a consideration of thefollowing description in conjunction with the drawing figures, in whichlike reference numerals are carried forward.

The example embodiments shown herein below of the measurement device areillustrative only and do not limit use for other parts of a body. Themeasurement device can be a tool, equipment, implant, or prosthesis thatmeasures at least one parameter or supports installation of prostheticcomponents to the musculoskeletal system. The measurement device can beused on bone, the knee, hip, ankle, spine, shoulder, hand, wrist, foot,fingers, toes, and other areas of the musculoskeletal system. Ingeneral, the principles disclosed herein are meant to be adapted for usein all locations of the musculoskeletal system.

At least one embodiment is directed to a system for adjusting ormonitoring a contact position of a musculoskeletal joint for stabilitycomprising: a prosthetic component configured to rotate after beingcoupled to a bone; a sensored prosthesis having an articular surfacewhere the sensored prosthesis is configured to couple to the prostheticcomponent, where the sensored prosthesis has a plurality of load sensorscoupled to the articular surface and a position measurement systemconfigured to measure position, slope, rotation, or trajectory, and aremote system configured to wirelessly receive quantitative measurementdata from the sensored prosthesis where the remote system is configuredto display the articular surface, where the remote system is configuredto display position of applied load to the articular surface, and wherethe remote system is configured to report impingement as themusculoskeletal joint is moved through a range of motion (ROM).

In general, the joint measurement system disclosed herein is directed toand can be used for any ball and socket joint of a musculoskeletalsystem. Typically, a first bone terminates in a ball-shaped surface andfits within a second bone having a cup that receives the ball. The firstbone is motivated by muscle, tendon, ligament, and tissue to move thefirst bone such that the ball of the first bone rotates within the cupof the second bone. A ball and socket joint has some of the widest rangeof motions of different joints within the musculoskeletal system. Forexample, the shoulder joint and the hip joint are ball and socketjoints. The shoulder joint and the hip joint are synovial joints havingsynovial fluid. The examples disclosed herein below are for a shoulderjoint system such as a reverse prosthetic shoulder joint or a standardprosthetic shoulder joint. The reverse prosthetic shoulder and thestandard shoulder have a cup and a ball as part of the joint system. Themeasurement device including the electronic circuitry and sensors can beadapted for either the curved surface of the cup or the curved surfaceof the ball of the shoulder joint system. All of the shoulder jointexamples disclosed herein can be also be used and sized for a hip. Themeasurement device disclosed herein can be adapted for either a curvedsurface of the acetabular cup of the hip or it can be adapted for acurved surface of a ball of a femoral head.

FIG. 1 is an illustration of a prosthetic shoulder joint 100 inaccordance with an example embodiment. The natural shoulder jointsupports a wide range of motion (ROM) when compared to other joints ofthe musculoskeletal system. The shoulder joint comprises a humerus, ascapula, coracoid process, acromion, and a clavicle. The shoulder jointis encapsulated by a synovial membrane that produces synovial fluid thatlubricates the shoulder joint and circulates nutrients to the area. Thescapula includes a glenoid cavity. The glenoid cavity has a curvedsurface. The proximal end of the humerus has a humeral head having acurved surface that couples to the glenoid cavity to support movementand establishes the range of motion of the shoulder joint. A humeralneck extends from the humerus and couples to the humeral head at apredetermined angle. Muscles, tendons and ligaments couple to thehumerus, scapula, and clavicle to hold the shoulder joint in place andto move the humerus in relation to the scapula.

Prosthetic shoulder joint 100 comprises a humeral prosthesis 102 and aglenoid prosthesis 114. Humeral prosthesis 102 includes a stem 104, aneck 106, and a head 108. Head 108 has an exterior curved surfaceconfigured to support movement of prosthetic shoulder joint 100. In oneembodiment, the exterior curved surface is convex. The proximal end of ahumerus 110 is cut to receive humeral prosthesis 102. Stem 104 isinserted into the medullary cavity of humerus 110 to couple humeralprosthesis 102 to humerus 110.

Glenoid prosthesis 114 comprises a glenoid structure 118 and retainingstructure 116. The glenoid cavity on scapula 112 is prepared to receiveglenoid prosthesis 114. Retaining structure 116 of glenoid prosthesis114 is configured to couple to scapula 112 to retain glenoid structure118. In one embodiment, glenoid structure 118 replaces the glenoidcavity. Glenoid structure 118 has an external curved surface. Glenoidstructure 118 is configured to couple to head 108 of humeral prosthesis102 to support movement of prosthetic shoulder joint 100. In oneembodiment, the external curved surface of glenoid structure is concave.The external curved surface of glenoid structure 118 is low friction tosupport movement under load by humeral prosthesis 102.

In one embodiment, glenoid prosthesis 114 is a trialing device thatincludes a trial measurement device. After measurements have been takenwith the trial measurement device the trialing device is removed and apermanent prosthesis is installed. Alternatively, glenoid prosthesis 114can comprise a tray coupled to retaining structure 116. A bearing havingan articular surface is configured to couple to the tray. In oneembodiment, the bearing can be removed from the tray and replaced withthe trial measurement device. A further example is a removable humeralhead 108 that can be replaced with the trial measurement device. In oneembodiment, the trial measurement device on humeral prosthesis 102 canoperate separately or in conjunction with the trial measurement devicethat replaces glenoid structure 118. In general, the trial measurementdevice will have at least one sensor configured to measure a parameter.The trial measurement device will have an external curved surface anddimensions similar to glenoid prosthesis 114 or humeral prosthesis 102.In one embodiment, measurements taken by the trial measurement devicewill relate to prosthetic shoulder joint 100 range of motion andstability.

FIG. 2 is an illustration of a prosthetic shoulder joint 120 inaccordance with an example embodiment. Prosthetic shoulder joint 120 isalso known as a reverse prosthetic shoulder joint. Prosthetic shoulderjoint 120 comprises a humeral prosthesis 122 and a glenoid prosthesis130. Humeral prosthesis 122 comprises a stem 124, a neck 126, and ahumeral liner 128. A proximal end of a humerus 110 is cut to receivehumeral prosthesis 122. Stem 124 is inserted into the medullary cavityof humerus 110.

Glenoid prosthesis 130 comprises a glenoid sphere 132 and a retainingstructure 134. The glenoid cavity of a scapula 112 is prepared forreceiving glenoid prosthesis 130. Retaining structure 134 of glenoidprosthesis 130 is configured to couple to scapula 112 to retain and holdglenoid sphere 132 in a position to couple to humeral prosthesis 122. Inone embodiment, glenoid sphere 132 is configured to couple to a surfaceof scapula 112 to replace the glenoid cavity. Glenoid sphere 132 has acurved surface configured to couple to humeral liner 128 of humeralprosthesis 122. Prosthetic shoulder joint 120 is a reverse shoulderbecause a glenoid sphere that corresponds to a humeral head of thehumerus is coupled to the scapula. Also, humeral liner 128 whichcorresponds to the glenoid cavity of scapula 112 is instead coupled tohumerus 110. Thus, the articulating surfaces have been reversed. In oneembodiment, an external curved surface of humeral liner 128 is concave.In one embodiment, the external curved surface of glenoid sphere 132 isconvex to couple to the humeral liner 128 and support movement ofprosthetic shoulder joint 120. The external curved surface of humeralliner 128 supports loading and is low friction to support movement ofprosthetic shoulder joint 120.

In one embodiment, humeral liner 128 can be removed and replaced with atrial measurement device. The trial measurement device can be coupled tothe neck of humeral prosthesis 122. For example, neck 126 of humeralprosthesis 122 can terminate in a tray configured to receive humeralliner 128. Humeral liner 128 is configured to be removable and replacedwith the trial measurement device. The trial measurement device willhave at least one sensor configured to measure a parameter. The trialmeasurement device will have an external curved surface and dimensionssimilar to humeral liner 128. In one embodiment, measurements taken bythe trial measurement device will relate to movement, loading, andstability of humeral prosthesis 122 in prosthetic shoulder joint 130. Inone embodiment, glenoid sphere 132 can be removed and replaced with asecond trial measurement device having at least one sensor. In oneembodiment, the second trial measurement device can be used instead ofthe first trial measurement device for assessing prosthetic shoulderjoint 130. In one embodiment, the first and second trial measurementdevices can both be used to provide measurement data for assessingprosthetic shoulder joint 130. Final prosthetic components are installedafter using the first or second trial measurement devices. In oneembodiment, one or more of the final prosthetic components can have atleast one sensor for measuring a parameter.

FIG. 3 is an illustration of a measurement device 154 in a shoulderjoint system 160 in accordance with an example embodiment. In theexample embodiment, a reverse shoulder joint is illustrated in themusculoskeletal system. Shoulder joint system 160 comprises computer162, glenoid sphere 152, and humeral prosthesis 158 includingmeasurement device 154. A glenoid sphere 152 is shown coupled to aprepared bone surface of scapula 140. The clavicle 142 and coracoidprocess 144 are shown in relation to the placement of glenoid sphere152. In one embodiment, the glenoid cavity of scapula 140 is prepared toreceive glenoid sphere 152. As shown, glenoid sphere 152 couples to aprepared bone surface 146 of scapula 140. Glenoid sphere 152 can have ananchor or stem to support attachment to scapula 140. In one embodiment,screws are used to couple glenoid sphere 152 to scapula 140. Glenoidsphere 152 has an external curved surface configure to couple tomeasurement device 154. In the example, glenoid sphere 152 has a convexsurface.

In one embodiment, a humeral prosthesis 158 is configured to couple to ahumerus 150. The proximal end of humerus 150 is cut to have a preparedbone surface 148 for receiving humeral prosthesis 158. The humeral linerhas a low friction surface and is configured to support movement ofshoulder joint system 160. The humeral liner is configured to couplehumeral tray 156. In the example, the humeral liner is configured to beremovable from humeral prosthesis 158 and is removed in FIG. 3 .Measurement device 154 replaces the humeral liner in humeral tray 156.In one embodiment, measurement device 154 is configured to bedimensionally equivalent to the humeral liner. In one embodiment, theexternal curved surface of measurement device 154 is concave and figuredto couple to the external curved surface of glenoid sphere 152.Measurement device 154 comprises at least one sensor and electroniccircuitry configured to control a measurement process and transmitmeasurement data to a computer 162 in proximity to shoulder joint system160. In one embodiment, measurement device 154 can further include aposition measurement system configured to measure position or movement.The at least one sensor will measure parameters of interest to supportinstallation of shoulder joint system 160. Typically, computer 162 is inan operating room outside the surgical field where shoulder joint system160 is being installed. A display 164 includes a graphical userinterface (GUI) that supports presenting measurement data in a graphicalmanner where an operating team can rapidly assimilate the measurementdata to verify, adjust or make changes that improve the installation.

In general, at least one component in shoulder joint system 160 hasmeasurement capability. In the example, shoulder joint system 160 is areverse shoulder system having measurement device 154. Measurementdevice 154 can be adapted for use in a standard shoulder joint systemcomprising a humeral prosthesis and a glenoid prosthesis. Sensors canalso be placed in one or both of the humeral prosthesis and glenoidprosthesis of the standard shoulder joint system. Measurement device 154is not limited to shoulder arthroplasty. Measurement device 154 can beadapted for use for hip, knee, spine, bone, ankle, wrist, fingers, toes,and other parts of the musculoskeletal system.

Quantitative measurement data is needed to kinetically assess andoptimize a shoulder joint during surgery. Measurement device 154delivers quantitative measurement data to a surgeon or surgical team inreal-time that support adjustment of the tension on different softtissues that enable the shoulder and affect range of motion of theshoulder. In one embodiment, measurement device 154 is a temporary ortrialing device that is dimensionally substantially equivalent to acorresponding permanent prosthesis. The permanent prosthesis thatreplaces measurement device 154 in the final prosthetic joint willmeasure similar to the measurement data provided by measurement device154.

Shoulder joint system 160 is taken through a range of motion (ROM) thatis measured by measurement device 154. For example, a position ofhumerus 150, a load magnitude applied to measurement device 154 byglenoid sphere 152, and a contact point where glenoid sphere 152 couplesto measurement device 154 can be measured in real-time through the ROM.Scapular notching is a common complication in a shoulder jointinstallation. Notching is caused by repetitive contact between humeralprosthesis 158 and the inferior scapular neck that causes an osteolyticreaction which results in polyethylene debris. Adjustments to shoulderjoint system 160 can be made when impingement is detected to preventscapular notching from occurring. The range of motion and loading ismonitored to determine whether to adjust tensions on various soft tissueelements enabling the shoulder movement. Adjustments to the soft tissueusing the quantitative measurement data can reduce or eliminateimpingement, create more stability in the shoulder joint, and increase arange of motion of the shoulder. More specifically, stability isenhanced by using measurements to reduce implant malpositioning, improvesubscapularis quality, and adjust muscle tensioning of the shoulderjoint. Proper compressive forces of the soft tissue at the glenohumeraljoint were found to significant improve stability in a reverse totalshoulder arthroplasty. Moreover, prosthesis designs which lateralize thehumerus are inherently more stable because they better tension therotator cuff and achieve more deltoid wrapping.

FIG. 4A is a flow diagram 170 for a shoulder joint installation usingmeasurement device 154 of FIG. 3 in accordance with an exampleembodiment. In the example, the measurement device disclosed in flowdiagram 170 corresponds to measurement device 154 and is configured tofit into a humeral prosthesis. The measurement device includes at leastone sensor and is configured to measure at least one parameter. In oneembodiment, the measurement device transmits measurement data to acomputer. The measurement data can be reviewed in real-time on a displaycoupled to the computer. In one embodiment, the measurement device isalso compatible with tensioning devices to allow functionality earlierin the surgery such as immediately after a humeral cut. The measurementdevice supports different size musculoskeletal systems and shoulderjoint systems where a single measurement device can support asubstantial portion of the population. In one embodiment, themeasurement device can be inserted into a humeral trial and implantwithout special tools. Similarly, the measurement device can be removedfrom the humeral trial and implant without special tools.

All steps may not be listed, for example steps known in the art that canbe used in the method. Also, the steps listed herein do not imply aspecific order and may be practiced in different orders depending on theapplication. In a step 172, the shoulder is exposed to gain access tothe humerus. In a step 174, the proximal end of the humerus is cut toprepare a humeral side. In one embodiment, the cut is made at apredetermined angle. In one embodiment, a prepared bone surface of thehumerus is configured to receive a humeral prosthesis. The stem of thehumeral prosthesis is inserted into the medullary canal of the humerusand placed in a predetermined position. The humeral prosthesis may alsoinclude a stem protector. In a step 176, the glenoid prosthesis isprepared for implantation. In one embodiment, one or more bone cuts orbone modifications are made to the scapula for receiving the glenoidprosthesis. In a step 178, the glenoid prosthesis is inserted andcoupled to the scapula. In a step 180, a trial implant is coupled to thehumerus. In a step 182, a measurement device size is determined for theshoulder application. In one embodiment, different sized measurementdevices can be provided for selection. Alternatively, different adapterscan be provided to assemble the measurement device for the appropriatesize. In a step 184, the measurement device is activated. In a step 186,the measurement device is assembled for an appropriate humeral option.The measurement device is configured to be adjusted such that a humeralneck angle of the humeral prosthesis can be changed. For example,different offsets can be chosen such as (0, 2.5, or 5 degrees) to affecta range of motion of the shoulder joint. In a step 188, a humeral trayand the measurement device are coupled to the humeral stem of thehumeral prosthesis. Thus, the glenoid prosthesis and the humeralprosthesis with the measurement device have been installed respectivelyto the scapula and the humerus. In a step 190, the shoulder is reduced.The shoulder is in place with the measurement device sending measurementdata to the computer. The display couples to the computer to display themeasurement data in real-time to a surgeon or surgical team.

In a step 192, the shoulder is evaluated through a range of motion(ROM). In one embodiment, the shoulder is moved through one or morepredetermined motions to indicate through measurement data, any issueswith the prosthetic shoulder joint installation. The measurement devicetransmits measurement data from the one or more sensors in themeasurement device to the computer. The measurement data is displayed inreal-time to the surgeon or surgical team. In one embodiment, some ofthe measurement data is processed by the computer and displayedgraphically on the display of the computer to support rapid assimilationof the measurement data by the surgical team. In a step 194, clinicallyappropriate adjustments are made based on measurement data from themeasurement device.

FIG. 4B is a continuation of flow diagram 170 from FIG. 4A for theshoulder joint installation using measurement device 154 of FIG. 3 inaccordance with an example embodiment. In a step 196, the humeral traytrial implant and the measurement device is removed from the humeralprosthesis. In a step 198, a humeral tray implant is installed onto thehumeral prosthesis. In one embodiment, the humeral tray implant is afinal implant and not a trialing device. In a step 200, the insertmeasurement device is coupled to the humeral prosthesis. In oneembodiment, the measurement device is coupled to the humeral trayimplant. In one embodiment, the trialing implant is dimensionallysimilar to the humeral tray implant such that measurement data takenwith the measurement device in the humeral tray should be substantiallyequal to the measurement data taken when the measurement device was inthe trial implant. In a step 202, the shoulder joint is reduced.

In a step 204, the shoulder is moved through a ROM. The measurementdevice transmits measurement data to the computer and is displayed onthe display. The measurement data is reviewed by the surgeon or surgicalteam to verify the previous clinically appropriate adjustments using thepermanent humeral tray implant coupled to the humeral prosthesis. In oneembodiment, further clinically appropriate adjustments can be made torefine or improve the shoulder joint based on the ROM results andquantitative measurement data. In a step 206, the measurement device isremoved from the permanent humeral tray implant. In one embodiment, themeasurement device is a disposable device that is disposed of after thesurgery is completed. In a step 208, a humeral liner is coupled to thehumeral tray implant. The humeral liner has a curved surface that isconfigured to couple to the glenoid implant. The humeral liner isdimensionally substantially equal to the measurement device. The humeralliner has a low friction surface that can withstand the loading appliedto the shoulder over a range of motion. In a step 210, the shoulderjoint is reduced. In a step 212, the wound is closed with the permanentshoulder prosthetic components in place. The permanent shoulder willperform equivalently to that measured and adjusted with the measurementdevice.

FIG. 5 is an exploded view of measurement device 154 illustratingcomponents in accordance with an example embodiment. In general,measurement device 154 generates quantitative measurement data targetedon clinical parameters that effect outcomes, impingement, stability, andrange of motion of the joint. In the example, measurement device 154 isconfigured to be used in a shoulder joint and more specifically in areverse shoulder joint. Measurement device 154 is configured to measurea functional load range and a maximum load range representative ofloading seen in a reverse shoulder joint. Measurement device 154 isconfigured to detect and report joint forces related to a glenoid spherecoupling to a humeral liner when the shoulder joint is being trialed.Measurement device 154 includes sensors to detect motion and orientationof a humeral prosthesis. Measurement device 154 is configured to detectinferior impingement on a humeral liner. Measurement device 154 isconfigured to measure superior impingement on the humeral liner.Measurement device supports an understanding of the soft tissues coupledto the shoulder joint, what soft tissues need to be evaluated and theconsequences of adjusting the soft tissue. In one embodiment, thetension of the different soft tissues coupled to the shoulder joint canbe evaluated and individually be adjusted within a predetermined rangethat results in optimal stability. Measurement device 154 is configuredto couple to a computer having a display. In one embodiment, thecomputer and display are within the operating room in view of thesurgical team to report the measurement data from measurement device154. Typically, the computer and the display are placed outside thesterile field of the operating room. Measurement device 154 includes alow power transceiver to support communications within the operatingroom but highly attenuated signals outside the operating room. Thecommunication can be secure by encrypting the transmission to preventthe measurement data from being read.

Measurement device 154 and the computer provide load and motion datawith minimal lag or delay. In one embodiment, lag or delay is typicallyless than 2 seconds. In one embodiment, measurement device 154 isdesigned for a single use and is provided in sterile packaging. In oneembodiment, a power source within measurement device 154 has sufficientpower for a single use but cannot power a second usage. In oneembodiment, measurement device 154 cannot be opened to replace the powersource. In one embodiment, a functional life for measurement device 154is approximately an hour to several hours in a surgical environment.Measurement device 154 comprises biocompatible materials. In oneembodiment, measurement device 154 is tested and calibrated beforesterile packaging to ensure optimal performance.

Measurement device 154 comprises an upper housing 220 and a bottomhousing 222. Upper housing 220 and bottom housing 222 are configured tocouple together to form a hermetically sealed enclosure. Sensors 230,electronic circuitry 236, and PC board 234 are hermetically sealedwithin the enclosure. In the example, upper housing 220 has an exteriorcurved surface 224 configured to couple to an external curved surface ofa glenoid sphere to support movement of the shoulder joint. Upperhousing 220 further includes a rim 242 that couples to external curvedsurface 224. In one embodiment, upper housing 220 and bottom housing 222have corresponding retaining features to hold upper housing 220 tobottom housing 222. Alternatively, screws can be placed through openings226 to couple upper housing 220 to bottom housing 222. Bottom housing222 has a mounting structure 240 configured to couple to a humeral trayof the humeral prosthesis. Glue or an adhesive may also be used tocouple upper housing 220 to bottom housing 222. Mounting structure 240aligns and retains the enclosure to the humeral prosthesis. Bottomhousing 222 includes openings 254 configured to receive structures fromupper housing 220. Openings 254 terminate to a reinforced area that isconfigured to receive the screws to hold upper housing 220 to bottomhousing 222. A flexible interconnect 228 is configured to couple toprinted circuit (PC) board 234. Flexible interconnect 228 couplessensors 230 to electronic circuitry 236. In one embodiment, electroniccomponents are mounted to PC board 234. PC Board 234 includesinterconnect to couple the electronic components to form an electroniccircuit configured to control a measurement process and transmitmeasurement data.

In one embodiment, sensors 230 are formed in flexible interconnect 228.Sensors 230 can be replicated accurately and have similarcharacteristics when formed at the same time in or on flexibleinterconnect 228. A reference sensor 232 can also be formed in or onflexible interconnect 228. For example, sensors 230 can be load sensors.The load sensors can be an elastic capacitor, a MEMs device, mechanicalstructure, hydraulic structure, pneumatic structure, strain gauge, atransducer, or a piezo-structure. The load sensors when coupled to aload convert the load to an electrical signal that is provided throughflexible interconnect 228 to electronic circuitry 236. Alternatively,sensors 230 can be discrete sensors that are coupled to flexibleinterconnect 228. In the example, sensors 230 as load sensors areelastic capacitors, MEMs devices, or piezo-structures. Sensors 230couple between upper housing 220 and bottom housing 222. In oneembodiment, sensors 230 couple to raised regions 238 on an interiorsurface 244 of bottom housing 222. Raised regions 238 each have asurface that is not co-planar to interior surface 244 of the bottomhousing. In one embodiment, there are an equal number of sensors 230 asraised regions 238. For example, three load sensors are used to measureloading applied to external curved surface 224. A load applied tosurface 224 of upper housing 226 by the glenoid sphere of the shoulderjoint is configured to compress sensors 230. In one embodiment, screwsin openings 226 that couple upper housing 220 to bottom housing 222 canbe adjusted to preload sensors 230 thereby placing sensors 230 in alinear operating region for the load range applied to measurement device154. Measurement device 154 can also be placed through a calibrationprocess to ensure optimal performance where each sensor can be measuredand correction applied to sensor measurement to ensure linear operationover a load range. The corrections are stored in memory where they canbe used to correct each sensor of the system.

FIG. 6 is an exploded side view of measurement device 154 in accordancewith an example embodiment. In one embodiment, the side view shows thatupper housing 220 couples to bottom housing 222 at a predetermined anglerelative to a bottom surface of mounting structure 240. Electroniccircuitry 236, PC board 234, flexible interconnect 228, and sensors 230are housed in the enclosure formed by upper housing 220 and bottomhousing 222. In one embodiment, electronic circuitry 236 and PC board234 are placed within a cavity within the interior of bottom housing222. Flexible interconnect 228 couples to a connector mounted on PCboard 234 to couples sensors 230 to electronic circuitry 236. Aninterior surface 256 of upper housing 220 includes raised regions 252.Raised regions 252 are sensor pads configured to couple to sensors 230.Raised regions 252 each have a surface that is not co-planar withinterior surface 256 of upper housing 220. In one embodiment, there arean equal number of raised regions 252 as sensors 230.

Upper housing 220 can be coupled to lower housing 222 by screws,retaining features, adhesive, welding, electrical means, magnetic meansor other sealing and fastening methodologies. Upper housing 220 andlower housing 222 can comprise a polymer, ceramic, metal, metal alloy,or material that can support loading of a musculoskeletal joint andprovides a low friction surface. In one embodiment, the materialcomprising upper housing 220 is low friction such that external curvedsurface 224 is low friction. Alternatively, a low friction coating canbe bonded or applied to upper housing 220 to provide a low frictionexternal curved surface 224. In the example shown herein above, upperhousing 220 couples to lower housing 222 by screws. Upper housing 220includes structures 250 corresponding to openings 254 of FIG. 5 . In oneembodiment, structures 250 are cylindrical in shape. A screw placedthrough an opening 226 couples through a corresponding structure 250.Structure 250 is a reinforced region of upper housing 220 configured toreceive a screw. In one embodiment, structures 250 aligns upper housing220 to bottom housing 222. Upper housing 220 aligns to bottom housing222 such that structures 250 of upper housing 220 couple into openings254 on surface 244 of bottom housing 222. In one embodiment, openings254 terminate to a reinforced region of bottom housing 222. Screwscouple through structures 250 and into the reinforced region in bottomhousing 222 to hold upper housing 220 to bottom housing 222. Asmentioned previously, the screws can be adjusted to seal the enclosureand preload sensors 230 for optimal performance.

FIG. 7 is an illustration of upper housing 220 coupled to bottom housing222 in accordance with an example embodiment. Upper housing 220 is atransparent to show underlying electronic circuitry 236, flexibleinterconnect 228, and sensors 230. Screws are placed in openings 226 andcouple to bottom housing 222 to hold upper housing 220 to bottom housing222. In one embodiment, three screws are used to hold upper housing 220to bottom housing 222.

Sensors 230 are shown coupling to raised regions 252 of upper housing220. Referring briefly to FIG. 6 , raised regions 252 are formed oninterior surface 256 of upper housing 220. Referring briefly to FIG. 5 ,sensors 230 also couple to raised regions 238 on interior surface 244 ofbottom housing 222. In one embodiment, raised regions 252 and raisedregions 238 have an area greater than or equal to the area of sensors230. Flexible interconnect 228 couples sensors 230 to electroniccircuitry 236 within the enclosure. In one embodiment, sensors 230comprise three sensors configured to measure loading applied to externalcurved surface 224 of upper housing 220. In one embodiment, the threesensors are equidistant from one another and located adjacent to rim 242of upper housing 220 underlying external curved surface 224. Each sensor230 is located at a predetermined location on external curved surface224. A pressure applied to surface 224 of upper housing 220 compressessensors 230 between raised regions 252 and raised regions 238 at thepredetermined locations. The measurement data from sensors 230 aretransmitted from measurement device 154 to computer 162 shown in FIG. 3within the operating room. The calibration data can be used to adjustthe measured output of sensors 230 at measurement device 154 prior totransmission or at computer 162 of FIG. 3 . Computer 162 includes adisplay 164 configured to provide information related to the measurementdata. In one embodiment, computer 162 is configured to calculate a loadmagnitude at a contact point on external curved surface 224 from themeasurement data from sensors 230. In the example, the contact point isan area or region of external curved surface 224 that couples to theglenoid sphere of a reverse shoulder joint. Computer 162 furthercalculates the position of the contact point on external curved surface224 from the measurement data from sensors 230 and the locations ofsensors on external curved surface 224. In one embodiment, themeasurement data can include data from a position or motion measurementsystem. The position or motion measurement system is part of electroniccircuitry 236. In one embodiment, the position measurement systemcomprises one or more inertial sensors. Data from the positionmeasurement system can be used to support the calculations andpresentations performed by computer 162 and displayed on display 164.

Sensors 230 can be tested and calibrated prior to packaging andsterilizing measurement device 154 to further linearize the output. Aspart of the calibration process the screws can be torqued to differentvalues to pre-load sensors 230. The pre-loading of sensors 230 cansupport operation of sensors 230 in a linear region of operation. Thecalibration data can be stored in memory as part of electronic circuitry236 and used to correct non-linearities of sensors 230 to provide moreaccurate measurement data. In the calibration process sensors will bezeroed or measure zero when the external curved surface 224 is unloaded.

FIG. 8 is a cross-section of measurement device 154 in accordance withan example embodiment. A cavity 260 is formed when upper housing 220couples to bottom housing 222. Electronic circuitry 236 on printedcircuit board 234 is placed in cavity 260. Cavity 260 includes at leastone retaining device to align and retain electronic circuitry 236 and PCboard 234. In one embodiment, sensors 230 are formed in or on flexibleinterconnect 238. Flexible interconnect 238 is patterned or formed toplace sensors 230 at predetermined locations. As shown, flexibleinterconnect 238 locates sensor 230 couples between raised region 252 onupper housing 222 and raised region 238 on bottom housing 222. In oneembodiment, a support structure 262 can extend from bottom housing 222towards upper housing 220 to retain flexible interconnect 238 centrallywithin measurement device 154.

FIG. 9 is an illustration of mechanical features of the enclosure ofmeasurement device 154 in accordance with an example embodiment.Measurement device 154 comprises an upper housing 220 and a bottomhousing 222 that forms an enclosure for electronic circuitry and one ormore sensors. As shown, upper housing 220 comprises a transparentmaterial to show underlying features in bottom housing 222. In oneembodiment, upper housing 220 and bottom housing 222 comprises abiocompatible material. In one embodiment, upper housing 220 and bottomhousing 222 can be molded or 3D printed with a polymer material.

Raised regions 238 are formed on interior surface 244 of bottom housing222. Raised regions 238 are sensor platforms that extend above interiorsurface 244 of bottom housing 222. In one embodiment, each raised region238 couples to a corresponding sensor. In the example, three raisedregions 238 are formed on interior surface 244. In one embodiment,sensors 230 are capacitors approximately 4 millimeters in diameterformed in flexible interconnect 228. In one embodiment, a capacitor canbe formed by a first interconnect and a second interconnect separated bya dielectric material within flexible interconnect 228. In oneembodiment, the dielectric material can be polyimide. In one embodiment,the capacitor can be shielded to minimize parasitic coupling ofcapacitance or signals to the capacitor. In one embodiment, raisedregions 238 are greater than or equal to 4 millimeters to supportsensors 230. A sensor snap 270 is a cutout on interior surface 244 ofbottom housing 222 in proximity to raised regions 238. The cutout ofsensor snap 270 supports retaining sensor 230 on a corresponding raisedregion 238.

A solder hole 272 is a cutout in bottom housing 222 to accommodateinterconnect that is used to couple batteries within the enclosure. Aflex snap 274 is a retaining feature configured to retain flexibleinterconnect 228 shown in FIG. 6 to bottom housing 222. In oneembodiment, flex snaps 274 comprises one or more columns that are formedon support structure 262. Flexible interconnect 228 has one or moreopenings corresponding to the one or more columns. Flex snaps 274 arepressed through corresponding openings of flexible interconnect 228 toalign and retain flexible interconnect 228 to support structure 262. Inone embodiment, flexible interconnect 228 is suspended above a rigidcutout 282 of bottom housing 222. In one embodiment, rigid cutout 282 isa large cutout area in bottom housing 222. Electronic circuitry 236 andPC board 234 as shown in FIG. 8 can be placed in rigid cutout 282. Rigidsnap 280 is a retaining feature configured to retain PC board 234 tobottom housing 222. In one embodiment, rigid snap 280 can be one or morecolumns configured to couple through one or more openings in PC board234 to align and retain PC board 234. In one embodiment, upper housing220 and bottom housing 222 have retaining features to couple upperhousing 222 to bottom housing 222. In one embodiment, an o-ring is usedto hermetically seal the enclosure. In one embodiment, the o-ringcircumferentially couples to bottom housing 222. In one embodiment, theo-ring locks into bottom housing 222. In one embodiment, a housing snap278 is one or more male retaining features on an exterior of bottomhousing 222. Housing snaps 278 couples through one or more correspondingopenings on upper housing 220 to align and retain upper housing 220 tobottom housing 222. In one embodiment, the o-ring is made of flexiblematerial and compresses to seal a surface of upper housing 220 and asurface of bottom housing 222 when retained by housing snap 278.Flexible o-ring compresses and seals the surface of upper housing 220and the surface of bottom housing 222. A compressed o-ring applies aforce that holds housing snaps 278 within the corresponding openings inupper housing 220. Tray rim 276 is an extrusion on bottom housing 222that couples to a humeral tray 156 of a humeral prosthesis 158 as shownin FIG. 3 and transfers loading applied to measurement device 154 to thehumeral tray.

FIG. 10 is a cross-sectional view of part of the enclosure illustratingsensor 230 between upper housing 220 and bottom housing 222 inaccordance with an example embodiment. In the example, external curvedsurface 224 of upper housing 220 couples to an external curved surfaceof glenoid sphere 152 as shown in FIG. 3 . In one embodiment, sensor 230is an elastic capacitive sensor integrated into flexible interconnect228 as shown in FIG. 7 . In one embodiment, the elastic capacitivesensor is approximately 0.012 inches thick. Sensor 230 is locatedadjacent to rim 242 of upper housing 220 underlying external curvedsurface 224 to maximize an area of measurement. The elastic capacitivesensor is engaged after assembly of upper housing 220 and bottom housing222. A gap of 0.010 inches thick is designed into upper housing 220 andbottom housing 222 to pre-load sensor 230 when upper housing 220 andbottom housing 222 are coupled together. In one embodiment, raisedregion 252 on interior surface 256 of upper housing 220 is flat. Sensor230 couples to raised region 252. In one embodiment, raised region 238on interior surface 244 is also flat. Sensor 230 couples to raisedregion 238. In the example, sensor 230 is coupled between raised regions252 and 238 respectively of upper housing 220 and bottom housing 220such that sensor 230 is compressed by 0.002 inches when upper housing220 is coupled to bottom housing 222. It has been found that the flatsurface of raised regions 252 and 238 reduces hysteresis of sensors 230thereby leading to more accurate load measurement. It has been furtherfound that surface roughness affects load measurement. In oneembodiment, the flat surfaces are formed smooth to improve measurementconsistency.

FIG. 11 is a cross-sectional view of measurement device 154 illustratingexternal curved surface 224 of upper housing 220 in accordance with anexample embodiment. Curved surface 224 is configured to couple to theexternal curved surface of glenoid sphere 152 as shown in FIG. 3 . Inone embodiment, sensors 230 comprise three sensors underlying upperhousing 220. The three sensors are located underlying external curvedsurface 224 near rim 242 of upper housing 220. The three sensors arespaced equidistant from one another. In one embodiment, raised regions252 and 238 respectively on upper housing 220 and bottom housing 222 arelocated in proximity to rim 242 to locate sensor 230 as high as possiblearound external curved surface 224 of upper housing 220. Placing sensors230 near rim 242 maximizes the sensing area that can be measured onexternal curved surface 224. In one embodiment, the three sensors areplaced 44 degrees from a gleno-sphere axis 290. An axis 292 of externalcurved surface 224 is shown relative to gleno-sphere axis 290. In theexample, arrows 294 and 296 are 44 degrees from gleno-sphere axis 290and indicate a location of sensors 230.

FIG. 12 is an illustration of sensor snap 270 formed in bottom housing222 in accordance with an example embodiment. Sensor snap 270 comprisescutouts 300 and wings 302. Sensors 230 are coupled to bottom housing 222in a manner to prevent movement during measurement. Any movement ofsensors 230 will introduce error to the measurement data. In theexample, movement of the elastic capacitor sensors formed in flexibleinterconnect 228 creates fluctuations in the capacitive measurements. Inone embodiment, wings 302 are formed in flexible interconnect 228 onopposing sides of sensor 230. Cutouts 300 are formed in interior surface244 of bottom housing 222. Cutouts 300 correspond to wings 302 formed inproximity to sensor 230. Wings 302 press-fit into cutouts 300, to alignand retain sensor 230 on raised region 238, and prevent movement ofsensor 230 during measurement. Press fitting wings 302 into cutouts 300have the added benefit of reducing assembly time. As an alternative tocutouts 300, posts can be formed extending from internal surface 244 ofbottom housing 222. The posts would be formed on opposing sides ofsensor 230 in proximity to sensor 230. The posts would couple tocorresponding openings in flexible interconnect 228 to align, retain,and prevent movement of sensor 230 on raised region 238. A furthermeasure to prevent movement would be to glue sensor 230 to raised region238, glue wings 302 into cutouts 300, or glue both sensor 230 and wings302 respectively to raised region 238 and cutouts 300.

FIG. 13 is a cross-sectional view of bottom housing 222 illustratingsolder hole 272 in accordance with an example embodiment. Solder hole272 is a cutout in bottom housing 222 for a solder battery connection310 to couple to PC board 234. As shown, solder hole 272 underlies PCboard 234. Solder battery connection 310 couples batteries 312 to abottom surface of PC board 234 to power electronic circuitry 236. In oneembodiment, solder hole 272 allows PC board 234 to lie flat on aninterior bottom surface of bottom housing 222. Solder hole 272 positionsbatteries 312 to allow coupling of flexible interconnect 223 to supportstructure 262.

FIG. 14 is an illustration of support structure 262 in bottom housing222 configured to couple to flexible interconnect 228 in accordance withan example embodiment. In one embodiment, support structure 262 extendsfrom an interior bottom surface of bottom housing 222. Support structure262 is centrally located in rigid cutout 282 as shown in FIG. 9 . In oneembodiment flexible interconnect 228 is rigidly coupled to supportstructure 262. Support structure 262 includes flex snaps 274. Flex snaps274 are columns extending from support structure 262. Flexibleinterconnect 228 has openings corresponding to flex snaps 274. In oneembodiment, flex snaps 274 are oversized or larger than the openings ininterconnect 228. The openings of flexible interconnect 228 are pushedon flex snaps 274 which press fits flexible interconnect to supportstructure 262.

Alternatively, pins can be used to couple flexible interconnect 228 tosupport structure 262. Both support structure 262 and flexibleinterconnect 228 have openings. Pins can be used to couple through theopenings in flexible interconnect 228 and into the openings in supportstructure 262. In one embodiment, the pins forcibly couple to theopenings of support structure 262 as an interference fit to retainflexible interconnect 228 to support structure 262. An adhesive couldalso be used to hold the pins to support structure 262.

In one embodiment, a surface of support structure 262 is not planar orparallel to the bottom surface of bottom housing 222. In the example,the surface of support structure 262 places flexible interconnect 228 ata 12.5 degree angle relative to the bottom surface of bottom housing222. The angle places flexible interconnect 228 in a position to supportplacement of sensors 230 as shown in FIG. 7 . Support structure 262 alsoplaces a connector of flexible interconnect 228 in a position to coupleto a connector on PC board 234. In one embodiment, flexible interconnect228 is suspended above the bottom surface of bottom housing 222.

FIG. 15 is a cross-sectional view of a portion of upper housing 220,bottom housing 222, and humeral tray 156 in accordance with an exampleembodiment. In the example, bottom housing 222 couples to humeral tray156 of humeral prosthesis 158. Humeral tray 156 typically comprises ametal such as stainless steel or titanium. Bottom housing 222 can have aretaining feature that couples to a corresponding retaining feature ofhumeral tray 156 such that measurement device 154 is retained butremovable from humeral tray 156. In the example, loading on externalcurved surface 244 of upper housing 220 is transferred through sensors230 as shown in FIG. 7 to bottom housing 222. The load distribution tosensors 230 can be unequal depending on the trajectory of the force toexternal curved surface 244. The loading couples through bottom housing222 and is distributed to humeral tray 156.

Upper housing 220 includes a sidewall 320 configured to couple to asidewall 328 of bottom housing 222. Sidewall 320 overlies a portion ofsidewall 328 of bottom housing 222 when upper housing 220 is coupled tobottom housing 222. In one embodiment, bottom housing 222 has an o-ring322 fitted around a circumferential groove in sidewall 328 of bottomhousing 222. O-ring 322 is configured to hermetically seal theenclosure. In one embodiment, o-ring 322 is compressed when sidewall 320of upper housing 220 overlies sidewall 328 of bottom housing 222. Aspreviously mentioned, coupling upper housing 220 to bottom housing 222pre-loads sensors 230 that corresponds to an external curved surface 244being unloaded.

Sidewall 328 of bottom housing 222 can have a protrusion 325 extendingpartially or circumferentially from sidewall 328. In one embodiment, afirst ledge of protrusion 325 couples to sidewall 320 of upper housing220 from above protrusion 325. In one embodiment, a second ledge ofprotrusion 325 couples to a rim 330 of humeral tray 156 from belowprotrusion 325. In one embodiment, loading is applied to external curvedsurface 244, through load the load sensors, to sidewall 328 of bottomhousing 222 to rim 330 and a surface of humeral tray 156 to distributeloading applied to measurement device 154 and to humeral prosthesis 158.Humeral tray 156 can have an o-ring 332 that aligns, retains, and sealsa portion of bottom housing 222 to humeral tray 156. In one embodiment,bottom housing 222 can have a corresponding groove that accommodateso-ring 332 when measurement device 154 is pressed into humeral tray 156.

FIG. 16 is an illustration of housing snap 278 on measurement device 154to couple upper housing 220 to bottom housing 222 in accordance with anexample embodiment. Housing snap 278 comprises a protrusion extendingfrom sidewall 328 of bottom housing 222. In one embodiment, sidewall 320of upper housing 220 is designed to flex. In one embodiment, sidewall320 has an opening configured to receive housing snap 278 to retainupper housing 220 to bottom housing 222. In one embodiment, upperhousing 220 slides onto bottom housing 222 such that sidewall 320 ofupper housing 220 overlies sidewall 328 of bottom housing 222. Upperhousing 220 and bottom housing 222 are compressed together until thehousing snap 278 on sidewall 328 couples through the correspondingopening in sidewall 320 of upper housing 220. In one embodiment, thehousing snap 278 has an angled or sloped wall 340 that facilitatessidewall 320 to flex and slide over the protrusion until housing snap278 engages with the corresponding opening. In one embodiment, more thanone housing snap 278 is used to retain upper housing 220 to bottomhousing 222. Alternatively, upper housing 220 can be screwed to bottomhousing 222 as disclosed in FIGS. 5-7 .

FIG. 17 is an illustration of rigid snaps 280 extending from bottomhousing 222 in accordance with an example embodiment. Rigid snaps 280are press fit columns extending from the interior bottom surface ofbottom housing 222. In one embodiment, rigid snaps 280 correspond toundersized openings in PC board 234. In the example, PC board 234 is amulti-layer rigid printed circuit board that interconnects electroniccircuitry 236 to form a circuit or system to control a measurementprocess and transmit measurement from measurement device 154. Rigidsnaps 280 are aligned to openings in PC board 234. Pressure is appliedto PC board 234 until rigid snaps 280 couple through the correspondingopenings in PC board 234. Rigid snaps 280 align and retain PC board 234within the enclosure. More specifically, rigid snaps 280 preventmovement of PC board 234 while in the shoulder joint. Movement of PCboard 234 can introduce movement to leads or flexible interconnectcoupling to PC board 234 thereby affecting measurement.

FIG. 18 is an illustration of o-ring 322 in measurement devices 154 inaccordance with an example embodiment. Bottom housing 222 has a rim 352.Sidewall 328 of bottom housing 222 can have a groove 350 around theperimeter to retain an o-ring 322 below rim 352. In one embodiment,o-ring 322 has a durometer of approximately shore 40. Rim 242 of upperhousing 220 overlies o-ring 322 when upper housing 220 couples to bottomhousing 222 as shown in FIG. 15 . O-ring 322 hermetically seals theenclosure and prevents the ingress of gas, liquids, or solids fromentering measurement device 154. Load measurement by measurement device154 is unaffected by o-ring 322.

FIG. 19 is an illustration of bottom housing 222 with electroniccircuitry 236 in accordance with an example embodiment. In oneembodiment, PC board 234 is a rigid printed circuit board coupled to theinterior bottom surface of bottom housing 222 through rigid snaps 280.Electronic circuitry 236 comprises electronic components such asprocessors, digital signal processors, digital logic circuitry,interface circuitry, analog circuitry, buffers, amplifiers, radiofrequency circuitry, sensors, passive components, and other circuitry.The electronic components can be mounted to PC board 234. PC board 234has multiple layers of interconnect to couple the electronic componentsto form a circuit that controls a measurement process and transmitsmeasurement data. Flexible interconnect 228 couples sensors 230 to PCboard 234. In one embodiment, flexible interconnect 228 is suspendedabove PC board 234 and couples to flex plug 362 mounted on PC board 234.Flex snaps 274 couple through openings in flexible interconnect 228 toretain, align, and prevent movement of flexible interconnect 228.Flexible interconnect 228 does not have any angled bends because theyhave been observed to cause sensor anomalies and errant data. In oneembodiment, flexible interconnect 228 has a shielding layer 374 toshield sensors 230 and interconnect. Shielding layer 374 is a groundedcopper layer that is external to the sensor ground that has showedsignificant noise improvement. Flexible interconnect 228 has a plug 372that couples to a flex plug 362 that couples to PC board 234. Flex plug362 couples sensors 230 to electronic circuitry 236. Batteries 312couple to PC board 234 via an interconnect 310 that underlies PC board234 in solder hole 312 as shown in FIG. 13 . In one embodiment,batteries 312 are configured to power measurement device 154 for asingle operation. An antenna 360 couples to a transceiver circuit on PCboard 234. Antenna 360 transmits measurement data from measurementdevice 154 within the operating room to computer 162 as shown in FIG. 3to provide the measurement data for use by a surgeon in real-time. Inone embodiment, measurement device 154 is disposed of in an appropriatemanner after the shoulder surgery is completed.

FIG. 20 is an illustration of flexible interconnect 228 in accordancewith an example embodiment. Flexible interconnect 228 includes sensors230 configured to measure a force, pressure, or load applied to themeasurement device. Sensors 230 can be coupled to flexible interconnect228 or formed as part of flexible interconnect 228. In one embodiment,sensors 230 are capacitors formed in flexible interconnect 228 using twoor more layers of interconnect. The capacitors comprise a first metalregion and a second metal region separated by a dielectric material. Inone embodiment, the capacitors are shielded to prevent noise couplingand to reduce parasitic coupling. In one embodiment, the capacitorscomprise more than one capacitor coupled in series or coupled inparallel. In one embodiment, the capacitors can comprise more than onedielectric layer. In general, the capacitors are elastic over a range ofoperation seen by a shoulder joint. Sensors 230 couple throughinterconnect in flexible interconnect 228 to a plug 372. Plug 372 isconfigured to couple to flex plug 362 on PC board 234 as shown in FIG.19 . In one embodiment, one or more reference sensors 370 are coupled toor formed in flexible interconnect 228. Reference sensors 370 are notconfigured to measure loading applied to the measurement device.Reference sensors 370 are formed identically to sensors 230. In oneembodiment, reference sensors 370 are located near sensors 230 to ensurestrong temperature and noise compensation for sensors 230. If a singlereference sensor 370 is used it can be located in an area substantiallyequidistant from sensors 370. Alternatively, the single reference sensor370 can be placed in proximity to one of sensors 370. In one embodiment,there is a reference sensor 370 for each sensor 230.

FIG. 21 is an illustration of measurement device 154 in accordance withan example embodiment. In general, a load applied by a prostheticcomponent coupled to external curved surface 224 will have no path toground except through the plurality of sensors measuring loading inmeasurement device 154. In one embodiment, there will be no parallelpaths to apply or dilute loading in measurement device 154. Measurementdevice 154 is designed to operate under a maximum load that is appliedto external curved surface 224 during installation into a prostheticjoint or when installed in the prosthetic joint. A compression strengthof measurement device 154 can accept the maximum load without impactingthe load path and accept the maximum load without plastic deformation.In one embodiment, measurement device 154 is configured to withstandtorque applied during a humeral reduction. Measurement device 154 has aform factor that matches a target trial implant for the prostheticjoint.

Upper housing 220 is coupled to bottom housing 222 to form the enclosurefor housing the power source, electronic circuitry, and one or moresensors. The power source can be a passive storage device, battery, orother means of providing power. Alternatively, power can be wired,inductively or RF coupled to measurement device 154. The power sourcehas sufficient energy to power the electronic circuitry and sensors fora single joint arthroplasty. Upper housing 220 is retained by one ormore housing snap 278 on sidewall 328 of bottom housing 222 couplingthrough an opening in sidewall 320 of upper housing 220. Housing snap278 has an angled or sloped wall 340 that facilitates sidewall 320 ofupper housing 220 to flex and slide over housing snap 278 until housingsnap 278 couples through the opening in sidewall 320 of upper housing220 to retain upper housing 220 to bottom housing 222. In the example,housing snap 278 is configured to keep housing 220 proximate to sensorengagement without applying a load when coupled to housing 222.

In the example, measurement device 154 couples to the humeralprosthesis. External curved surface 224 couples to a glenoid spherecoupled to a scapula to support movement of a shoulder. In oneembodiment, measurement device uses three sensors to measure load andposition of load on external curved surface 224. In one embodiment, atleast one reference sensor can also be used to improve the accuracy ofthe load measurements from each sensor. The interface between theexternal curved surface 224 and sensors 230 is fully constrained. In oneembodiment, the sensing configuration of measurement device 154 usesexactly three load sensors for full constraint if sensors 230 areoriented towards a center of curvature of external curved surface 224such that all force vectors pass through a same point with no moments tobalance. In one embodiment, measurement device 154 measures loadingapplied to external curved surface 224 in a range of 10-60 lbs. for theshoulder application. The accuracy of the measured load magnitude is 3.5lbs. or less. In one embodiment, the range and accuracy can be adjustedby changing parameters of the capacitor sensor such as dielectricthickness or sensor area. The measured capacitance value correlates toloading applied to external curved surface 224. Alternatively, differentsensor types such as a MEMs, strain gauge, or piezo-sensor could be usedin place of the capacitor. Measure device 154 can be operated with asafe overload of 200 percent of the maximum load range. In the example,the position of applied load or contact point of the glenoid sphere onexternal curved surface 224 has an accuracy of 2 millimeter and 2degrees or less. This accuracy is given for reference and can be changedor improved depending on the application and requirements of themeasurement device. The shoulder joint can be moved through a range ofmotion and measurement device 154 will provide measurement data inreal-time. The measurement data is transmitted to computer 162 in theoperating room where computer 162 receives and processes the measurementdata and displays the measurement data on display 164 in a form that canbe rapidly assimilated by the surgeon and surgical team to supportvalidation or adjustment with quantitative measurement data.

FIG. 22A is an illustration of a GUI 380 on display 164 of computer 162in accordance with an example embodiment. Measurement device 154 is in ashoulder joint and transmitting measurement data as shown in FIG. 3 .Components of FIGS. 3, 7, 8, 9, and 21 may be referred to in thediscussion herein below to relate operation of measurement device 154 towhat is displayed in GUI 380. In general, a surgeon moves the shoulderthrough a free range of motion to generate measurement data to determinestability of the shoulder joint. The measurement data from the sensorsin measurement device 154 is transmitted to computer 162. Computer 162processes the information and displays the information in a manner wherequantitative measurement data can be rapidly assimilated by the surgeonor surgical team. The measurement data can be displayed or it can bepresented graphically or audibly.

A picture of a portion of measurement device 154 is displayed on display164. In the example, a surface 384 is displayed on display 164 thatcorresponds to external curved surface 224 as shown in FIG. 21 . In oneembodiment, display 164 depicts a curved surface of a ball or socketprosthetic joint system. In one embodiment, radial measurement data fromload sensors at predetermined locations as disclosed in FIGS. 29A-31herein below is used to determine contact point 384 on display 164. Inother words, the movement of contact point 384 is not measured,depicted, or calculated for display 164 as a planar measurement butillustrates movement on a curved surface. Display 164 can further addmeasurement data or graphics to disclose movement of contact point 384on external curved surface 224. In one embodiment, movement of contactpoint 384 will be non-linear. In one embodiment, display 164 may displaya three dimensional type of animation to illustrate to a surgeon orsurgical team a location of contact point 384 on external curved surface224. This allows the surgeon to understand loading or location on a ballor cup of a prosthetic joint system. Alternatively, more than one viewor different orientations of external curved surface 224 can be providedon display 164 to better illustrate a location of contact point 384 onexternal curved surface 224. In a reverse shoulder joint, externalcurved surface 224 couples to a glenoid sphere. A contact point 382 orload centroid location is represented on GUI 380 where the glenoidsphere applies loading to external curved surface 224 of measurementdevice 154. Contact point 382 is shown on surface 384 of GUI 380. Adisplay box 386 discloses the load magnitude in real-time on GUI 380 asthe shoulder joint is moved through the range of motion. In oneembodiment, computer 162 or measurement device 154 can include softwarehaving a force location and load magnitude algorithm that calculatescontact point 382 and load magnitude as displayed in display box 386from the measurement data received from measurement device 154. In theexample, the measurement data comprises information from three sensorsmeasuring loading applied to external curved surface 224, at least onereference sensor, and a position measurement system. The positionmeasurement system is configured to measure position or motion. In oneembodiment, the position measurement system is configured to be housedin measurement device 154. In one embodiment, the position measurementsystem is an inertial measurement unit (IMU). Computer 162 ormeasurement device 154 can further have quaternion and range of motionalgorithms to support measurement of movement and position. Calibrationinformation can be accessed for the IMU or load sensors and used withthe force location, load magnitude, and impingement measurements. In oneembodiment, calibration information or calibration data corresponds totest measurements on measurement device 154. In one embodiment, thecalibration data can be stored on non-volatile memory such as EEPROMwithin measurement device 154. As the shoulder joint is moved through apredetermined range of motion there will be a minimum load magnitudemeasured at a first location and a maximum load magnitude measured at asecond location on surface 384 for the predetermined range of motion.The minimum load magnitude is indicated in display box 388 on GUI 380that is continuously updated should a lower value occur. Similarly, themaximum load magnitude is indicated in display box 390 on GUI 380 thatis continuously updated. In one embodiment, force vector data can beused to detect impingement. GUI 380 will notify the surgeon or surgicalteam when impingement is detected by audible, visual, or haptic means.In one embodiment, the IMU comprises one or more inertial sensors and ishoused in measurement device 154. The IMU can track position, motion,and can also be used in conjunction with the force vector data or aloneto determine impingement.

In the example, an exit button 492, a LOG button 494, a zero button 496,a reset button 392, and a ROM button 470 are provided on GUI 380. In oneembodiment, exit button 492 toggles between connecting measurementdevice 154 and disconnecting measurement 154 from computer 162. In oneembodiment, exit button 492 will indicate when measurement device 154 iscoupled to computer 162. In one embodiment, enabling LOG button 494 logsdata for 10 seconds. In one embodiment, enabling zero button 496 zeroesload data offsets. In one embodiment, enabling reset button 392 resetsdisplay box 388 and display box 390 to the current load magnitude value.In one embodiment, enabling ROM button 370 initiates a range of motiontest. ROM button 370 further initializes the IMU for the range of motiontest. Battery indicator 526 indicates an amount of power left in thepower source. In the example, the power source is one or more batteriesand battery indicator 526 indicates the percentage of power remaining inthe batteries of measurement device 154 or provide an estimation of anoperating time of measurement device 154 based on the average currentdrain from the batteries. GUI 380 further includes a tracking functionthat displays dynamic motion of contact point 382 through the full rangeof motion to evaluate joint kinetics. GUI 380 can also indicate or leavea location trace where loading exceeds a predetermined threshold.

FIG. 22B is an illustration of GUI 380 indicating impingement inaccordance with an example embodiment. Components of FIGS. 3, 7, 8, 9 ,and 21 may be referred to in the discussion herein below to relateoperation of measurement device 154 to what is displayed in GUI 380. GUI380 shows contact point 382 on surface 384 corresponding to the contactpoint on surface 224 of measurement device 154. In the example, contactpoint 382 is calculated from quantitative measurement data frommeasurement device 154 and is updated in real-time as the shoulder jointis moved through a range of motion.

Measurement device 154 couples to computer 162 that can be indicated onGUI 380. An indicator 528 on GUI 380 shows the signal strength of thewireless connection to measurement device 154. A signal strength isdisplayed on indicator 528 that provides an indication of the connectionand ability to transfer measurement data to computer 162. In oneembodiment, the wireless connection is a Bluetooth low energy connectionthat opens a connection dialog between computer 162 any Bluetoothdevices. Computer 162 is used to select measurement device 154 forconnection and initiates the wireless connection. In one embodiment,calibration data and device information from measurement device 154 isdownloaded to computer 162. Measurement device 154 couples to computer162 and begins to stream measurement data. In one embodiment, GUI 380zeroes any load data and then begins showing a measured load magnitudeat contact point 382 in display box 386.

In a first step, the ROM button 470 is enabled preparing for measurementdevice 154 to measure the shoulder joint as it is moved through apredetermined range of motion. The position measurement system isenabled for measurement. In the example, the position measurement systemis an inertial measurement unit. In a second step, the shoulder joint isheld motionless at zero degrees adduction for 5 seconds. In a thirdstep, GUI 380 is configured to display a notification to begin movementin abduction. In a fourth step, during the movement, the degrees ofrotation and plot will be updating. In a fifth step, at the end of themovement (e.g. full abduction) the user will hold the arm motionless. Ina sixth step, measurement data will be captured during the movement andROM button 470 will indicate that the measurement has ended. In oneembodiment, ROM button 470 will change color when the measurement hasended.

Impingement occurs when a prosthetic joint impinges on bone or softtissue. In the example, scapular notching occurs when the prostheticshoulder joint impacts bone as some point in the range of motion.Scapular notching typically occurs during an adduction movement.Impingement may also occur in the soft tissue around the prostheticshoulder joint. Soft tissue impingement is often called acromialimpingement. Impingement information can be displayed on GUI 380. In oneembodiment, a rim 520 is used to show if impingement occurs andapproximately where the impingement occurs. A portion of rim 520 will behighlighted by a color change or a gray scale change on the portion ofrim 520 in proximity to where the impingement occurs. In one embodiment,the portion of rim 520 in proximity to the impingement will turn redwhen impingement is detected. In one embodiment, a plot 522 is displayedon GUI 380. Plot 522 shows range of motion angles versus loading forcontact point 382.

FIG. 23 is an illustration of GUI 380 on display 164 coupled to computer162 displaying sensor information related to range of motion frommeasurement device 154 in accordance with an example embodiment. In theexample, measurement device 154 is in the reverse shoulder joint asshown in FIG. 3 . Components of FIGS. 3, 7, 8, 9, and 21 may be referredto in the discussion herein below to relate operation of measurementdevice 154 to what is displayed in GUI 380. The measurement datacomprises data from sensors 230 coupled at predetermined positions inmeasurement device 154 to measure loading applied to external curvedsurface 224. In one embodiment, the predetermined positions of sensors230 are used to calculate the position of load and the magnitude of loadapplied to external curved surface 224. In one embodiment, themeasurement data can further comprise information from the positionmeasurement system. In one embodiment, the position measurement systemcomprises one or more inertial measurement units for tracking positionand motion.

Computer 162 converts measurement data from measurement device 154 to agraphical form that a surgeon or surgical team can rapidly assess astatus of the shoulder joint. A display box on GUI 380 can be used toprovide numerical information related to a parameter measurement. In theexample, the shoulder joint can be moved through specific orpredetermined range of motions. A motion bar is used to provideinformation on a predetermined range of motion. The motion bar is a toolof GUI 380 that allows the surgeon to rapidly assess the movement todetermine if the shoulder joint functions with known norms or could usefurther optimization to affect loading or range of motion.Alternatively, a round graphic can be used with a rim and indicatorwhich rotates around it to read for the angle. As shown, four motionbars are displayed on GUI 380. Each motion bar corresponds to a specificmovement of the shoulder joint. In the shoulder example each motion barwill indicate a maximum range of motion for an internal motion and anexternal motion for the specific movement. As shown, the internal motionmaximum is indicated on a left side of the motion bar and a numericalvalue for the maximum internal motion is listed below the motion bar onthe left side. The external motion maximum is indicated on a right sideof the motion bar and a numerical value for the maximum internal motionis listed below the motion bar on the right side. A center or zerobetween internal and external motion is indicated by a bar central tothe motion bar. In general, the actual range of motion as the surgeonmoves the installed prosthetic joint with measurement device 154 will beless than the internal motion maximum or the external motion maximum. Afirst display box will indicate the numerical load magnitude applied tomeasurement device 154. A second display box indicates the maximum rangeof motion (in degrees) achieved by internal movement of the prostheticjoint (by the surgeon) relative to the internal motion maximum. Thesecond display box is placed on the left side of the motion bar andabove the motion bar. A third display box indicates the maximum range ofmotion (in degrees) achieved by external movement of the prostheticjoint (by the surgeon) relative to the external motion maximum. Thethird display box is placed on the right side of the motion bar andabove the motion bar.

The motion bar in GUI 380 graphically displays the same information asthe display boxes but in a manner that can be rapidly assimilated toreduce an assessment time. In one embodiment, the surgeon can use themotion bars to determine if the loading and range of motion is within anacceptable range without looking at numerical values. As mentionedpreviously, the motion bar length indicates a range maximum frominternal motion maximum to external motion maximum. The range of motionof the movement by the surgeon of the prosthetic joint can be indicatedby a color scale region within the motion bar. The range of motion ofthe movement of the surgeon can also be indicated by a grey scale regionwithin the motion bar. A color scale can be used in within the motionbar to indicate the magnitude of loading at different points within therange of motion. The color scale can be a load magnitude or correspondto a predetermined load magnitude range over the range of motion.Similarly, the grey in the grey scale region can indicate the magnitudeof loading. Each shade of grey can be a load magnitude or correspond toa predetermined load magnitude range. In one embodiment, the surgeondoes not need to know the absolute load magnitude at each point over therange of motion but that the load magnitudes are within a predeterminedrange over the range of motion. The surgeon can “at a glance” determinethat the color within the motion bar is correct or that the loading orrange of motion is incorrect. In one embodiment, the color or colorscale corresponds to an acceptable predetermined range of the loadmagnitude for the shoulder joint based on clinical evidence thatprovides optimum performance. In one embodiment, the colors or shades ofgray displayed in the motion bar indicate a pattern that the surgeon islooking for over a specific movement of the prosthetic joint. Forexample, the color scale or grey scale can change as the movement movesto the internal or external maximum. For example, the surgeon can view agrey scale indicating optimal loading over a predetermined rangecentered between the internal and external movement. Moving outside thepredetermined range towards the maximum internal movement or the maximumexternal movement results in increased or decreased loading that is lessthan optimal. In general, the surgeon can “at a glance” determine wherethe optimal loading occurs and at where it is located in the range ofmotion. The motion bar can also indicate loading or range of motionissues that need to be addressed. For example, adjustments can be madeif the loading is non-symmetric about the internal/external movementcenter, if the optimal loading range does not cover a sufficient rangeof movement, or if there are loading problems at the extremes.Alternatively, the colors or shades of gray are chosen to allow thesurgeon to rapidly assess where the load magnitude is outside thepredetermined range and at what range in the movement (e.g. internalmotion or external motion) the load magnitude is outside thepredetermined range. For example, green can indicate the load magnitudeis within a predetermined range. Yellow/Orange can indicate the loadmagnitude is bordering on being outside the predetermined range. Red canindicate that the load magnitude is higher than acceptable. Blue canindicate that the load magnitude is lower than acceptable. Thus, thesurgeon does not need to review numbers but at a glance can determine ifthe load magnitude over the range of motion is acceptable or needs to beadjusted. The surgeon can then make adjustments such as soft tissuetensioning, modifying a bone surface, changing position of the implant,or shimming the implant to change the load magnitude to be within thepredetermined range to name but a few.

Typically, the surgeon is trying to achieve an acceptable range ofmotion for the internal motion and the external motion of a particularmovement of the joint. In one embodiment, the acceptable range of motioncan be indicated by dashed lines on the motion bar. A first dashed lineis indicated on the internal motion side of the bar. A second dashedline is indicated on the external motion side of the bar. The surgeoncan determine at a glance of the motion bar if the color scale region orthe grey scale region overlies the dashed lines or falls short of theacceptable range of motion (defined by the dashed lines) for theinternal motion or external motion of the joint movement. Thus, GUI 380supports rapid assessment of the joint status as it relates to the rangeof motion and loading over the range of motion. In one embodiment,computer 162 can analyze the measurement data and provide a detailedworkflow of the corrections or adjustments to achieve the desired rangeof motion and loading for the kinetic assessment of the prostheticjoint.

In the example of a shoulder joint, a ROM button 470 is enabled on GUI380 to initiate a range of motion measurement. Display 164 can beoperated via touch screen, remote control, audio control, keyboard, orother device. In the example, GUI 380 shows four motion bars on display164 after ROM button 470 is enabled. The four motion bars are a motionbar 400, a motion bar 402, a motion bar 404, and a motion bar 406. Eachmotion bar has a start/stop button for initiating or stopping ameasurement. Although four motion bars are shown in the example, more orless can be displayed depending on the application or joint type. In theexample, motion bar 400, motion bar 402, motion bar 404, and motion bar406 respectively have a start/stop button 430, a start/stop button 432,a start/stop button 434, and a start stop button 436. Each motion barrepresents a type of movement for a prosthetic shoulder joint that ismeasured. Motion bar 400 represents a movement comprisinginternal/external rotation at zero degrees abduction. Motion bar 402represents a movement comprising internal/external rotation at 45degrees abduction. Motion bar 404 represents a movement comprisinginternal/external rotation at zero degrees adduction. Motion bar 404represents movement of the shoulder joint in extension and flexion.

In the example, start/stop button 432 is enabled to begin a measurement.In one embodiment, all other range of motion tests are disabled whenstart/stop button 432 is enabled. In one embodiment, starting a new testwill reset or redo a finished test. A bar 426 appears across motion bar402 to indicate position of the shoulder joint within the range ofmotion of the selected movement. The shoulder joint is moved through theinternal/external rotation at 45 degrees abduction. GUI 380 furtherincludes display boxes 414 and 416 in proximity to and above motion bar402. GUI 380 also displays a maximum rotation of internal rotation (70degrees) and the maximum rotation of external rotation (90 degrees)shown respectively at a left end and below motion bar 402 and at a rightend and below motion bar 402. Realistically, maximum rotation or maximummovement both internal and external is not often achievable for jointinstallations. An acceptable range of movement for the installedshoulder joint is indicated by dashed line 444 corresponding to internalrotation of the shoulder joint at 45 degrees abduction and dashed lines446 corresponding to external rotation of the shoulder joint at 45degrees abduction. The actual measured movement range from internal toexternal corresponds to the color scale region or the gray scale region462 within motion bar 402. Note that gray scale region 462 overliesdashed line 444 on the left side of motion bar 402 and overlies dashedline 446 on the right side of motion bar 402. Gray scale region 462indicates that the installed prosthetic shoulder joint has an acceptablerange of motion for internal/external rotation at 45 degrees abduction.Gray scale region 462 also indicates the loading over the range ofmotion of the shoulder joint at 45 degrees abduction. The loadingapplied at the current location is also shown in display box 428. Thegray scale used in gray scale region 462 indicates loading at differentpoints in the range of motion. The surgeon can review gray scale region462 at a glance to determine if the loading is correct around themovement center between internal and external rotation, if the loadingis correct for a sufficient range of motion around the movement center,and behavior or transition of the loading to the internal rotationmaximum and the external rotation maximum of the shoulder joint. Thesurgeon can then perform adjustments to change the loading profile andrange of motion indicated by motion bar 402. As mentioned previously,computer 162 can provide a work flow that provides the adjustments thatcan be monitored in real-time to produce change in the measurement datarelated to motion bar 402 to produce more optimal loading and range ofmotion.

Motion bar 400, 404, and 406 are disabled during the shoulder range ofmotion measurement with the internal/external rotation at 45 degreesabduction for motion bar 402 of GUI 380. Motion bar 400 measures ashoulder range of motion having an internal/external rotation at zerodegrees abduction when start/stop button 430 is enabled. In the example,the maximum internal rotation is 70 degrees and the maximum externalrotation is 80 degrees for motion bar 400. Dashed lines 440 and 442respectively indicate an acceptable range of motion for theinternal/external rotation at zero degrees abduction. Dashed line 440couples through motion bar 400 on the left side corresponding tointernal rotation. Dashed line 442 couples through motion bar 400 on theright side corresponding to external rotation. The color scale or grayscale region 460 is shown in motion bar 400. The measured range ofmotion of the internal rotation at zero degrees adduction is indicatedin display box 410 on GUI 380. Similarly, the measured range of motionof the external rotation at zero degrees abduction is indicated indisplay box 412.

Motion bar 404 measures a shoulder range of motion having aninternal/external rotation at zero degrees adduction when start/stopbutton 434 is enabled. In the example, the maximum internal rotation is70 degrees and the maximum external rotation is 90 degrees for motionbar 404. Dashed lines 448 and 450 respectively indicate an acceptablerange of motion for the internal/external rotation at zero degreesadduction. Dashed line 448 couples through motion bar 404 on the leftside corresponding to internal rotation. Dashed line 450 couples throughmotion bar 400 on the right side corresponding to external rotation. Thecolor scale or gray scale region 464 is shown in motion bar 404. Themeasured range of motion of the internal rotation at zero degreesadduction is indicated in display box 418 on GUI 380. Similarly, themeasured range of motion of the external rotation at zero degreesadduction is indicated in display box 420.

Motion bar 408 measures a shoulder range of motion in extension andflexion when start/stop button 436 is enabled. In the example, themaximum extension is 45 degrees and the maximum flexion is 175 degreesfor motion bar 408. Dashed lines 452 and 454 respectively indicate anacceptable range of motion for extension and flexion of the shoulderjoint. Dashed line 452 couples through motion bar 408 on the left sidecorresponding to the shoulder joint in extension. Dashed line 454couples through motion bar 408 on the right side corresponding to theshoulder joint in flexion. The color scale or gray scale region 466 isshown in motion bar 408. The measured range of motion of the shoulderjoint in extension is indicated in display box 422 on GUI 380.Similarly, the measured range of motion of the shoulder joint in flexionis indicated in display box 424.

FIG. 24 is an illustration of an option screen 482 in accordance with anexample embodiment. Referring briefly to FIG. 23 , an options button 480is pressed on GUI 380 and returns option screen 482. Option screen 482allows the user to change a color scale 472 or gray scale region inmotion bar 474 that relates color scale 472 or gray scale to measuredloading of the joint. Display boxes 476 and 478 respectively indicate alow and a high load value for color scale 472 or gray scale region. Inone embodiment, there are four values for setting load range for eachcolor or gray shade. In one embodiment, if a gradient map is selected toindicate loading, a used or acceptable value of loading should be amid-point of color range 472 or gray scale. In one embodiment, if asolid map is selected to indicate loading, a used value should representmaximum loading for that color range or gray scale. The selected colorscale 472 or grey scale range will take effect after exiting optionsscreen 482. In one embodiment, a redo of the test will result inredrawing motion bar 474 with the new color range or gray scale enteredin option screen 384 after enabling return button 470.

FIG. 25 is an illustration of a range of motion (ROM) overlay 390 on GUI380 in accordance with an example embodiment. Referring briefly to FIG.23 , the shoulder joint is taken through four different motions and themeasurement data stored. Enabling the ROM display button 490 displaysROM overlay 390. In the example, GUI 380 graphically displays themovement of contact point 382 to external curved surface 384 on GUI 380for each of the four different shoulder joint movements measured in FIG.23 . As previously mentioned, contact point 382 corresponds to thecontact point of the glenoid sphere on external curved surface 224 ofthe shoulder joint. Contact point 382 is calculated from measurementdata from load sensors or the IMU in measurement device 154 as shown inFIG. 21 . The movement of contact point 382 for a predetermined movementis called a load track. In one embodiment, this is not an active screenor real-time measurement. ROM overlay 390 uses stored measurement datafrom each of the movements. A load track 500 corresponds to the internaland external movement at zero degrees abduction. A load track 502corresponds to the internal and external movement at 45 degreesabduction. A load track 504 corresponds to the internal and externalmovement at zero degrees adduction. A load track 506 corresponds to themovement in extension and flexion of the shoulder joint. Thus, themovement of contact point 382 can be understood for each differentmovement that is measured and used to determine if a problem may existin the pattern of movement and the load magnitude at specific points inthe movement. In one embodiment, the loading value can be indicatedacross a load track by color scale or gray scale shade. In oneembodiment, computer 162 can analyze the load tracks and provide aworkflow to correct or optimize the shoulder joint based on thequantitative measurement data.

FIG. 26 is an illustration of GUI 380 showing an impingement range ofmotion assessment in accordance with an example embodiment. EnablingI-ROM button 512 produces a graph 514 where trace 510 is continuouslyactive. In one embodiment, the arm and shoulder joint is moved in a“windmill” motion. Trace 510 corresponds to a position of the humerusrelative to adduction (graph Y-axis-humerus Z-axis) and horizontalflexion (graph X-axis, humerus Y-axis) is rendered. Track button 516 canbe toggled to collect trace data or reset trace for a new datacollection. In one embodiment, the measurement ignores theinternal/external rotation of the arm. Furthermore, the area covered bytrace 510 are the limits of abduction/adduction and horizontal flexion.

FIG. 27A is an illustration of measurement data from measurement device154 in accordance with an example embodiment. FIG. 27B is anillustration of measurement device 154 transmitting measurement data tocomputer 162 and displaying the measurement data on display 164 inaccordance with an example embodiment. Display 164 includes GUI 380 tosupport rapid assimilation of measurement data. Housing 220 is madetransparent to show placement of electronic circuitry 236 and sensors530, 532, and 534. Sensors 530, 532, and 534 underlie external curvedsurface 224 of housing 220. In one embodiment, measurement device 154shows orientation when placed in a shoulder joint such as a superiorposition 580, an inferior position 582, an anterior position 586, and aposterior position 584. Sensor seating is configured to orient sensors530, 532, and 534 toward a center of curvature of external curvedsurface 224. Sensors 530, 532, and 534 correspond to sensors 230 asshown in FIG. 19 but are individually identified to disclose placementor location within measurement device 154 relative to superior position580, inferior position 582, anterior position 586, and posteriorposition 584 in the shoulder joint. Sensors 530, 532, and 534 arerespectively labeled S3, S6, and S8 on measurement device 154.Measurement device 154 also has a reference sensor 536 labeled S5. Aspreviously mentioned, sensors 530, 532, and 534 are spaced equidistantfrom each other and located as close to rim 242 as possible to maximizethe measurement area. As shown, sensor 530 is located in proximity tosuperior position 580. Sensor 532 is located between posterior position584 and inferior position 582. Sensor 534 is located between anteriorposition 586 and inferior position 582. Thus, measurement data from eachsensor can be correlated to the movement to better understand howshoulder position affects loading. Measurement data from sensors 530,532, 534, reference sensor 536 is transmitted wirelessly to computer162. The measurement data from sensors 530, 532, and 534 is used tocalculate a load magnitude and a contact point by computer 162 onexternal curved surface 224 of measurement device 154 of FIG. 21 .Display 164 coupled to computer 162 can display the load magnitude andthe contact point for viewing by the surgeon and surgical team.

In the example, a shoulder implant is installed in a shoulder of apatient. Measurement device 154 is inserted in the shoulder joint andpowered on. The shoulder is moved through predetermined range ofmotions. The measurement data from measurement device 154 is captured bycomputer 162. In one embodiment, the shoulder can be forced from aneutral position to impingement. Display 164 provides a graph 572showing load data from sensors 530, 532, 534, reference sensor 536, anda sum of sensors 530, 532, and 534 as the shoulder joint is movedthrough different predetermined motions. Graph 572 is illustrative ofwhat a surgeon or surgical might see if the measurement data from eachsensor was provided graphically. Sensors 530, 562, 564, and 568 arerepresented by different colors, gray scale shades, or patterned lineson graph 572 as indicated by a legend 574. In legend 574, sensor key 560illustrates measurement data on graph 572 related to sensor 530 (S3).Sensor key 562 illustrates measurement data on graph 572 related toreference sensor 536 (S5) in proximity to superior position 580 ofmeasurement device 154. Sensor key 564 illustrates measurement data ongraph 572 related to sensor 532 (S6) between posterior position 584 andinferior position 582 of measurement device 154. Sensor key 568illustrates measurement data on graph 572 related to sensor 534 (S8)between anterior position 586 and inferior position 582 of measurementdevice 154. Finally, a sum key 570 illustrates measurement data on graph572 related to a sum of load measurement data related to sensors 530(S3), 532 (S6), and 534 (S8).

Box 540 of graph 572 corresponds to a neutral shoulder rotation inadduction. Measurement data from sensors 530 (S3), 532 (S6), and 534(S8) indicate that sensor 534 is more heavily loaded than sensors 530(S3) and sensor 532 (S6) during the neutral shoulder rotation inadduction. Reference sensor 536 (S5) is not loaded in the example. Theloading on sensor 534 (S8) varies between 5 lbs. to 17 lbs. during theneutral shoulder rotation in adduction. Sum 570 looks similar to sensor534 (S8) during the neutral shoulder rotation in adduction because theload contributions of sensors 530 (S3) and 532 (S6) are small. Ingeneral, the surgeon can see graphically where the loading occursrelative to the movement and what each sensor is measuring in theneutral shoulder rotation in adduction.

Box 542 of graph 572 corresponds to an external shoulder rotation inadduction. Measurement data from sensors 530 (S3), 532 (S6), and 534(S8) indicate that sensors 530 (S3) and sensor 534 (S8) have a loadingless than sensor 532 (S6) during the external shoulder rotation inadduction. Reference sensor 536 (S5) is not loaded in the example. Theloading on sensor 532 (S6) varies between 7 lbs. to 15 lbs. during theexternal shoulder rotation in adduction. Sum 570 looks similar to sensor532 (S6) during the external shoulder rotation in adduction because theload contributions of sensors 530 (S3) and 535 (S8) are small. Ingeneral, the surgeon can see graphically where the loading occursrelative to the movement and what each sensor is measuring in theexternal shoulder rotation in adduction.

Box 544 of graph 572 corresponds to an internal shoulder rotation inadduction. Measurement data from sensors 530 (S3), 532 (S6), and 534(S8) indicate that all sensors 530 (S3), sensor 532 (S6), and sensor 534(S8) have significant loading of greater than 10 lbs. during theinternal shoulder rotation in adduction. Reference sensor 536 (S5) isnoisy during this measurement having a loading as high as 5 lbs. duringthe measurement. As previously mentioned, these are just example graphsof measurements. In the initial part of the internal shoulder rotationin adduction, sensor 534 (S8) has a reading of greater than 40 lbs.where it is greatly reduced to under 20 lbs. thereafter. Conversely, theinitial part of the internal shoulder rotation in adduction, sensors 530(S3) and 532 (S6) have a reading of no loading and a loading of greaterthan 10 lbs. thereafter. The loading on sensor 532 (S6) varies between 7lbs. to 15 lbs. during the external shoulder rotation in adduction. Sum570 combines the loading of sensors 530 (S3), 532 (S6), and 534 (S8)during the internal shoulder rotation in adduction which exceeds 50 lbs.in portions of the rotation. In general, the surgeon can see graphicallywhere the loading occurs relative to the movement and what each sensoris measuring in the internal shoulder rotation in adduction.

Box 546 of graph 572 corresponds to a neutral shoulder rotation inabduction. Measurement data from sensors 530 (S3), 532 (S6), and 534(S8) indicate that sensors 530 (S3) and sensor 534 (S8) are loaded lessthan sensor 532 (S6) during the neutral shoulder rotation in abduction.Reference sensor 536 (S5) is unloaded. The loading on sensor 532 (S6)varies between 12 lbs. to greater than 40 lbs. during the neutralshoulder rotation in abduction. Sum 570 looks similar to sensor 532 (S6)during the neutral shoulder rotation in abduction but load components ofsensors 530 (S3) and 534 (S8) do contribute such that sum 570 does notoverlap sensor key 564 during the neutral shoulder rotation inabduction. In general, the surgeon can see graphically where the loadingoccurs relative to the movement and what each sensor is measuring in theneutral shoulder rotation in abduction.

Box 548 of graph 572 corresponds to an external shoulder rotation inabduction. Measurement data from sensors 530 (S3), 532 (S6), and 534(S8) indicate that sensors 530 (S3) and sensor 534 (S8) are loaded lessthan sensor 532 (S6) during the external shoulder rotation in abduction.Reference sensor 524 (S5) is unloaded. The loading on sensor 532 (S6)varies between 13-16 lbs. during the external shoulder rotation inabduction. Sum 570 looks similar to load data from sensor 532 (S6)during the external shoulder rotation in abduction but differs becauseloading from sensors 530 (S3) and 534 (S8) are added. In general, thesurgeon can see graphically where the loading occurs relative to themovement and what each sensor is measuring in the external shoulderrotation in abduction.

Box 550 of graph 572 corresponds to an internal shoulder rotation inabduction. Measurement data from sensors 530 (S3), 532 (S6), and 534(S8) indicate that sensors 530 (S3) and sensor 534 (S8) are loaded lessthan sensor 532 (S6) during internal shoulder rotation in abduction.Reference sensor 524 (S5) is unloaded. The loading coupled to sensor 532(S6) varies between 15-19 lbs. during the internal shoulder rotation inabduction. Sum 570 looks similar to load data from sensor 532 (S6)during the external shoulder rotation in abduction but differs becauseloading from sensors 530 (S3) and 534 (S8) are added. In general, thesurgeon can see graphically where the loading occurs relative to themovement and what each sensor is measuring in the internal shoulderrotation in abduction.

FIG. 28 illustrates a cross-sectional view of external curved surface224 of measurement device 154 as shown in FIG. 21 in accordance with anexample embodiment. In the example, three sensors are used to measureloading and position of load where the glenoid sphere contacts and loadsexternal curved surface 224. The three sensors are equidistant from oneanother. Sensor 530 and sensor 532 are shown in the cross-sectionalview. A center 589 of the glenoid sphere is shown with an axis 588 ofthe glenoid sphere indicated by a dashed line. Sensor 530 is an angle ϕfrom axis 588 of the glenoid sphere. Similarly, sensor 532 is an angle ϕfrom axis 588 of the glenoid sphere. In one embodiment, impingement isdetected when a measured force angle α is greater than the angle ϕ.Alternatively, impingement can be detected when the measured force angleα does not correlate to the assumptions such as the applied force isnormal to external curved surface 224, the reaction forces are detectedto the center of rotation, there are no moment arms, and simple forcebalancing applies. In one embodiment, the position measurement system oran IMU can be used to measure a first angle α. A second angle α can bemeasured with the measurement data from the three sensors. The first andsecond angle α can be compared to one another as a redundancy check orto determine if the measurement is outside the angle ϕ to determineimpingement.

FIG. 29A is an illustration of a spherical coordinate system 600 forcalculating force and position in accordance with an example embodiment.In one embodiment, spherical coordinate system 600 is natural and can beused to mathematically describe external curved surface 224 ofmeasurement device 154 as shown in FIG. 21 . External curved surface 224of measurement device 154 couples to a prosthetic component of a jointand is configured to support movement of the joint. In the example, anorigin 602 of spherical coordinate system 600 is the center of curvatureof external curved surface 224. The positive Z-axis extends from origin602 to external curved surface 224 intersecting a plane equidistant fromeach sensor coupled to external curved surface 224. A point in sphericalcoordinate system 600 can be defined by a radius r, an angle θ, and anangle ϕ as shown in FIG. 29A. In the example, the radius r is a radiusof curvature of curved surface 224. Theta (θ) is an angle measured fromradius r to the Z-axis. Phi (ϕ) is an angle measured from the X-axis anddashed line 604. Dashed line 604 can be calculated by the equation 1r×sin(ϕ) on FIG. 29A. Dashed line 604 is on the X-Y plane. Note that anexternal curved surface that is convex (a ball of the joint instead ofthe cup) can be modeled similarly.

FIG. 29B is an example of force and position calculations related tosensor location in accordance with an example embodiment. Referringbriefly to FIG. 27B, sensors 530, 532, and 534 are configured to measurea force, pressure, or load applied to external curved surface 224 ofmeasurement device 154. As mentioned previously, the sensor locationsand the force and position calculations can correspond to either a ballshaped prosthetic component or a cup shaped prosthetic component. Ingeneral, sensors 530, 532, and 534 are placed equidistant from eachother and have a maximum radius of circle on external curved surface 224defined by sensors 530, 532, and 534. Referring briefly to FIG. 27B andFIG. 29B sensor 530 is located in proximity to superior position 580which is called herein as a top sensor of measurement device 154. Sensor532 is between posterior position 584 and inferior position 582 which iscalled a bottom left sensor herein. Sensor 534 is between anteriorposition 586 and inferior position 582 which is called a bottom rightsensor herein. In the example, radius r is given a value of 0.748 inchesfor a prototype measurement device 154. Sensors 530, 532, and 534 arelocated as close to the X-Y plane on curved surface 224 as possible tomaximize the measurement area on external curved surface 224.

In the example, the radial position of sensors 530, 532, and 534 aredescribed in equation 2 of FIG. 29B. The angle θ_(s) is an anglemeasured from the Z-axis such that each sensor 530, 532, and 534 islocated on dashed circle 606. The angular positions of sensors 530, 532,and 534 are defined in equation 3 of FIG. 29B. The angular position isrelative to the X-axis. Sensor 530 is located at ϕ₁π/2 on dashed circle606. Sensor 534 is located at ϕ₂=11π/6 on dashed circle 606. Sensor 532is located at ϕ₃=7π/6 on dashed circle 606. In one embodiment, a sensorunit vector represents the direction from the sensor to origin 602. Thesensor unit vector is the assumed direction of the sensor reactionforce. The equation for the unit vectors related to sensors 530, 532,and 534 are defined by equation 4 where sensors 530, 534, and 532respectively correspond to unit vector Ŝ₁, Ŝ₂, and Ŝ₃ on FIG. 29B.Sensor 530 has a unit vector Ŝ₁=(0, −0.695, −0.719) in polar coordinateswhich is the top sensor as shown in FIG. 27B. Sensor 534 has a unitvector Ŝ₂=(−0.602, 0.347, 0.719) in polar coordinates which is thebottom right sensor as shown in FIG. 27B. Sensor 532 has a unit vectorŜ₃=(0.602, 0.347, −0.719) in polar coordinates which is the bottom leftsensor as shown in FIG. 27B.

FIG. 30 is a diagram showing a force magnitude calculation frommeasurement data from sensors 530, 532, and 534 in accordance with anexample embodiment. The force magnitude calculation can be used for ameasurement device as a ball or a measurement device as a cup. Thus,measurement device 154 can be implement for a reverse shoulder, regularshoulder, femoral head of a femoral prosthetic component of a hip, or anacetabular cup of a hip. It is assumed in the calculation of the forcemagnitude and position of applied force that there is no friction onexternal curved surface 224 of measurement device 154 as shown in FIG.21 . The interface between external curved surface 224 and sensors 530,532, and 534 as shown in FIG. 27B are fully constrained. In oneembodiment, only sensors 530, 532, and 534 are used for full constraintif sensors 530, 532, and 534 are oriented towards the center ofcurvature of external curved surface 224 such that all force vectorspass through the same point and there are no moments to balance.Reaction force vectors are assumed to be normal to external curvedsurface 224, and therefore pass through the same point in space atorigin 602 that is the center of curvature. In general, sensors 530,534, and 532 measures loading applied to external curved surface 224where a scalar reaction force is respectively represented by S₁, S₂, andS₃ for the above listed sensors. Reaction force vectors {right arrowover (S)}₁, {right arrow over (S)}₂, and {right arrow over (S)}₃ aregiven by equation 5 of FIG. 30 where i is 1, 2, or 3 respectivelycorresponds to sensors 530 (top sensor), 534 (bottom right sensor), and532 (bottom left sensor). As mentioned previously, reaction forcevectors {right arrow over (S)}₁, {right arrow over (S)}₂, and {rightarrow over (S)}₃ couple through origin 602. The total reaction force{right arrow over (F)}_(r) is given by equation 6 of FIG. 30 which isthe sum of the reaction force vectors {right arrow over (S)}₁, {rightarrow over (S)}₂, and {right arrow over (S)}₃. A balance of forcesrequires that the applied force vector {right arrow over (F)}_(a)applied to external curved surface 224 is equal to the negative of thetotal reaction force {right arrow over (F)}_(r) as shown in equation 7of FIG. 30 . Applied force vector {right arrow over (F)}_(a) couples toa contact point 610 on external curved surface 224 of measurement device154. In the reverse shoulder joint example, contact point 610corresponds to a location where a glenoid sphere applies a force,pressure, or load to measurement device 154 for the measurement datafrom sensors 530, 532, and 534. Applied force vector {right arrow over(F)}_(a) also couples through origin 602 if the tail is extended. Thecombined force magnitude can be broken down into X-axis, Y-axis, andZ-axis force components measured by load sensors 530, 532, and 534 asshown by equation 8 of FIG. 30 that corresponds to equation 7. The loadmagnitude applied to external curved surface 224 can be calculated fromthe measurement data from sensors and more specifically from F_(ax),F_(ay), and F_(az) previously calculated in equation 8 from the scalarreaction forces of sensors 530, 532, and 534 broken into X-axis, Y-axis,and Z-axis components and summed. The reported load measured usingmeasurement data from sensors 530, 532, and 534 is ∥{right arrow over(F)}_(a)∥ and can be calculated by equation 9 of FIG. 30 which is thesquare root of the sum of the squares of F_(ax), F_(ay), and F_(az)calculated. Thus, the load magnitude at contact point 610 can becalculated in real-time from the measurement data from sensors 530, 532,and 534.

FIG. 31 is a diagram showing a position of applied load calculation onexternal curved surface 224 of measurement device 154 using measurementdata from sensors 530, 532, and 534 in accordance with an exampleembodiment. Referring briefly to FIG. 22A, contact point 382 isindicated on surface 384 of GUI 380 and display 164. Note that surface384 is a two-dimensional image of a three dimensional curved surface.Accurate placement of a contact point on a two dimensional image of athree dimensional curved surface is disclosed herein below for GUI 380.In the example, the point of load application in R³ is projected ontothe X-Y plane to display load position. In the example, a point 612(x_(a), y_(a)) is the projected load position on the X-Y plane. In oneembodiment, the applied force vector {right arrow over (F)}_(a) isconverted to a positional vector {right arrow over (P)}_(a) with thesame direction and magnitude of r as shown in equation 10 of FIG. 31 .Positional vector {right arrow over (P)}_(a) couples to external curvedsurface 224 at contact point 610 and also couples through origin 602.The projection of {right arrow over (P)}_(a) onto the X-Y plane is givenby equation 11 which is (x_(a), y_(a))=(P_(ax), P_(ay)). Thus, contactpoint 610 can be accurately represented on a two-dimensional display forview by the surgeon or surgical team in real-time.

In one embodiment, measurement data from force sensors 530, 532, and 534are used to detect impingement corresponding to FIG. 22B. For example,impingement caused repeatable load spikes peripherally. Load spikes of10-30 lbs. occur near an impingement point are captured in themeasurement data and used to detect impingement. A force magnitude andcontact point where a prosthetic component couples external curvedsurface 224 of measurement device 154 is calculated from measurementdata from sensors 530, 532, and 534 as disclosed herein above. Aposition measurement system can also provide measurement data to supportthe force magnitude and contact point measurement. In the examplecertain assumptions are made in the calculations. Sensors 530, 532, and534 are placed equidistant from one another at positions that maximizethe radius of circle defined by the sensors. Sensors 530, 532, and 534are oriented such that sensor reaction forces are directed to a centerof curvature of external curved surface 224. In one embodiment, it isassumed that no frictional forces or negligible frictional forces occuron external curved surface 224 or at a sensor interface. In oneembodiment, reaction force vectors are assumed to be normal to externalcurved surface 224 and therefore pass through the center of curvature ofexternal curved surface 224. There can only be specific combination offorces possible when utilizing one or more of the assumptions disclosedherein above when calculating the load magnitude and the contact pointusing the forces applied to sensors 530, 532, and 534. In oneembodiment, force combinations that are outside the one or moreassumptions can mean that the measured force or measured forces bysensors 530, 532, and 534 are not normal to external curved surface 224of measurement device 154. Alternatively, the force vector may not passthrough the center of curvature of external curved surface 224. Anycombination of forces measured by sensors 530, 532, and 534 outside thepossible combinations determined by one or more assumptions disclosedherein should be reviewed or considered as impingement. Furthermore,time based analysis of the load data from sensors 530, 532, and 534 canbe used and correlated against known impingement to detect impingement.As mentioned previously, abrupt changes in the measured load vector alsoequates to impingement. In one embodiment, the position measurementsystem such as an IMU (inertial measurement unit) can be used to monitormovement and correlate against known joint movement for a particularmotion to detect abnormalities that indicate impingement. The jointgeometry may also be susceptible to impingement in specific directions.If so, predetermined movements can be performed on the joint todetermine if impingement occurs and adjustments made based onquantitative measurement data.

FIG. 32 is a block diagram of electronic circuitry 236 in measurementdevice 154 in accordance with an example embodiment. In general,electronic circuitry 236 couples to one or more sensors to measure oneor more parameters. Components of FIGS. 3, 5-21 may be referred to inthe discussion herein below to relate operation of measurement device154 to electronic circuitry 236. The sensors can measure parameters suchas, height, length, width, tilt/slope, position, orientation, loadmagnitude, force, pressure, contact point location, displacement,density, viscosity, pH, light, color, sound, optical, vascular flow,visual recognition, humidity, alignment, position, rotation, inertialsensing, turbidity, bone density, fluid viscosity, strain, angulardeformity, vibration, torque, elasticity, motion, acceleration,infection, pain, and temperature to name but a few. In the example,electronic circuitry 236 is configured to control a measurement process,receive measurement data from sensors 230, receive measurement data fromposition measurement system 742, and transmit the measurement data tocomputer 162 for further analysis and feedback. More specifically,sensors 230 measure a force, pressure, or load at predeterminedlocations of external curved surface 224. Sensors 230 at thepredetermined locations comprise sensor 530, 532, and 534 as shown inFIG. 27B. Position measurement system 742 measures position, movement,rotation, velocity, acceleration, or distance. In one embodiment,position measurement system comprises an inertial measurement unit (IMU)744 configured to measure 9 degrees of freedom. IMU 744 can comprise oneor more inertial sensors. In one embodiment, sensors 230 and positionmeasurement system 742 is housed in measurement device 154.

Electronic circuitry 236 comprises power management circuitry 700,control logic 702, memory 704, interface circuitry 706, positionmeasurement system 742, and wireless communication circuitry 720. Apower source 740 couples to electronic circuitry 236 to power ameasurement process. Power source 740 can be an inductor, supercapacitor, storage cell, wired power, wireless power, solar cell, energyharvesting device, or other energy storage medium. In one embodiment,power source 740 comprises batteries 312. Electronic circuitry 236further includes a transceiver that can be positioned on or within, orengaged with, or attached or affixed to or within, a wide range ofphysical systems including, but not limited to instruments, equipment,devices, prosthetic components, or other physical systems for use on orin human bodies and configured for sensing and communicating parametersof interest in real time. Electronic circuitry 236 is coupled togetherto form an electronic system using multiple layers of interconnect onprinted circuit board 234. Flexible interconnect 228 can be used tocouple electronic circuitry 236 to sensors 230 that are remotelylocated.

Electronic circuitry 236 can be configured to provide two-waycommunication between measurement device 154 and computer 162. In oneembodiment, measurement device 154 provides quantitative measurementdata related to a shoulder joint installation. Measurement device 154 isconfigured to provide quantitative measurement data related to loadmagnitude, position of applied load, position, and rotation. Themeasurement data from measurement device 154 is used by computer 162 ina kinematic assessment to support installation of prosthetic componentsto ensure optimal loading, balance, stability, alignment, range ofmotion, and reduce impingement that improves performance and reliabilitybased on clinical evidence.

Power source 740 provides power to electronic circuitry 236 and sensors230. The power source 740 can be temporary or permanent. In oneembodiment, the power source is not rechargeable. Measurement device 154is disposable after a single use and the power in batteries 312 areinsufficient for a second surgery. Measurement device 154 would bedestroyed or disposed of after being used. Alternatively, power source740 could be rechargeable. Measurement device 154 would be sterilizedbefore being reused. Charging of power source 740 can comprise wiredenergy transfer or short-distance wireless energy transfer. A chargingpower source to recharge power source 740 can include, but is notlimited to, a battery or batteries, an alternating current power supply,a radio frequency receiver, an electromagnetic induction coil, aphotoelectric cell or cells, a thermocouple or thermocouples, or atransducer energy transfer. In one embodiment, energy transfer to powersource 740 could be allowed for the single application scenario if powersource 740 has insufficient energy to finish the surgery. Furthermore,measurement device 154 can utilize power management circuitry 700 tominimize the power drain of power source 740 while in use or whenelectronic circuitry 236 is idling.

As previously mentioned, power source 740 in measurement device 154comprises batteries 312. Batteries 312 can be recharged by the methodsdisclosed herein above. Alternatively, power source 740 can be a supercapacitor, an inductor, or other energy storage device. An externalcharging source can be coupled wirelessly to the rechargeable battery,capacitor, or inductive energy storage device through an electromagneticinduction coil by way of inductive charging. The charging operation canbe controlled by power management circuitry 700 within electroniccircuitry 236. In one embodiment, power management circuit 700 supportsoperation of measurement device 154 during charging thereby allowing thesurgery to continue if a low charge on power source 740 is detected. Forexample, power can be transferred to batteries 312, capacitive energystorage device, or inductive energy storage device by way of efficientstep-up and step-down voltage conversion circuitry. This conservesoperating power of circuit blocks at a minimum voltage level to supportthe required level of performance.

Power management circuitry 700 is configured to operate under severepower constraints. In one embodiment, power management circuitry 700controls power up, power down, and minimizes power usage duringoperation. The power management circuitry 700 is configured to reducepower dissipation during operation of the system. The power managementcircuitry 700 can turn off or reduce the power delivered to circuitsthat are not being used in a specific operation. Similarly, if thesystem is idle and not being used, the power management circuitry 700can put other unused circuitry in a sleep mode that awakens prior to thenext measurement being made. Power management circuitry 700 can includeone or more voltage regulation circuits that provide a plurality ofdifferent stable voltages to electronic circuitry 236 and sensors 230.

In one configuration, a charging operation of power source 740 canfurther serve to communicate downlink data to electronic circuitry. Forinstance, downlink control data can be modulated onto the energy sourcesignal and thereafter demodulated from an inductor in electroniccircuitry 230. This can serve as a more efficient way for receivingdownlink data instead of configuring an internal transceiver withinelectronic circuitry 230 for both uplink and downlink operation. As oneexample, downlink data can include updated control parameters thatmeasurement device 154 uses when making a measurement, such as externalpositional information or for recalibration purposes. It can also beused to download a serial number or other identification data.

Control logic 702 controls a measurement process or sequence thatengages the sensors, converts the measurement data into a useableformat, and transmits the information. Control logic 702 can comprisedigital circuitry, a microcontroller, a microprocessor, an ASIC(Application Specific Integrated Circuit), a DSP (Digital SignalProcessing), a gate array implementation, a standard cellimplementation, and other circuitry. Control logic 702 couples to memory704. Memory 704 is configured to store measurement data, softwareroutines, diagnostics/test routines, calibration data, calibrationalgorithms, workflows, and other information or programs. In oneembodiment, one or more sensors may be continuously enabled and sampledperiodically to control logic 702. Control logic 702 controls themeasurement process, stores the measurement data in memory, or transmitthe measurement data in real-time. Control logic 702 can includededicated ports that couple to a sensor to continuously receivemeasurement data or receive updated measurements at high sample rates.Alternatively, control logic 702 can select a sensor to be measured. Forexample, multiple sensors can be coupled to control logic 702 via amultiplexer. Control logic 702 controls which sensor is coupled throughthe multiplexer to sample and output the measurement data. Multiplexedmeasurement data works well when the measurement data is not critical orcan be sampled occasionally as needed. Control logic 702 can also selectand receive measurement data from different sensors in a sequence orsimultaneously through parallel channels. Control logic 702 can beconfigured to monitor the measurement data from a sensor but transmitmeasurement data only when a change occurs in the measurement data.Furthermore, control logic 702 can modify the measurement data prior totransmitting the measurement data to computer 162. For example, themeasurement data can be corrected for non-linearity using calibrationdata. In one embodiment, a microcontroller with Bluetooth low energy(BLE) is used with an analog to digital converter to convert analogvalues to digital.

Interface circuitry 706 couples between sensors 230 and control logic702. Interface circuitry 706 supports conversion of a sensor output to aform that can be received by computer 162. Interface circuitry 706comprises digital circuitry and analog circuitry. The analog circuitrycan include multiplexers, amplifiers, buffers, comparators, filters,passive components, analog to digital converters, and digital to analogconverters to name but a few. In one embodiment interface circuitry 706uses one or more multiplexers to select a sensor for providingmeasurement data to control logic 702. Control logic 702 is configuredto provide control signals that enable the multiplexer to select thesensor for measurement. The multiplexer can be enabled to deliver themeasurement data to control logic 702, memory 704, or to be transmitted.Typically, at least one analog to digital conversion or digital toanalog conversion of the measurement data occurs via the interfacecircuitry 706.

Sensors 230 couple through interface circuitry 706 to control logic 702.Alternatively, interface circuitry 706 can couple directly to circuitryfor transmitting measurement data as it is measured. The physicalparameter or parameters of interest measured by sensors 230 are force,pressure, or load as disclosed herein but sensors 230 can furtherinclude other sensors that measure height, length, width, tilt/slope,position, orientation, load magnitude, force, pressure, contact pointlocation, displacement, density, viscosity, pH, light, color, sound,optical, vascular flow, visual recognition, humidity, alignment,rotation, inertial sensing, turbidity, bone density, fluid viscosity,strain, angular deformity, vibration, torque, elasticity, motion, andtemperature. Often, a measured parameter is used in conjunction withanother measured parameter to make a kinetic and qualitative assessment.In joint reconstruction, portions of the musculoskeletal system areprepared to receive prosthetic components. Preparation includes bonecuts or bone shaping to mate with one or more prosthesis. Parameters canbe evaluated relative to orientation, stability, alignment, impingement,direction, displacement, or position as well as movement, rotation, oracceleration along an axis or combination of axes by wireless sensingmodules or devices positioned on or within a body, instrument,appliance, vehicle, equipment, or other physical system.

Sensors 230 can directly or indirectly measure a parameter of interest.For example, a load sensor in measurement device 154 can comprise acapacitor, a piezo-sensor, or a MEMs sensor that can compress as loadingis applied to the load sensor. Measuring load with a capacitor is anindirect form of sensing as the capacitance value of the capacitor willchange with the amount of loading applied to the capacitor. Thecapacitive measurement data can be sent to computer 162 for furtherprocessing. Computer 162 can include software and calibration datarelated to the elastic capacitors. The load measurement data can beconverted from capacitance values to load measurements. Computer 162 canstore calibration data that can be used to curve fit and compensate fornon-linear output of a sensor over a range of operation. Furthermore,the individual sensor measurement can be combined to produce othermeasurement data by computer 162. In keeping with the example of loadmeasurement data, the individual load measurement data can be combinedor assessed to determine a location where the load is applied to asurface to which the load sensors couple. The measurement data can bedisplayed on a display that supports a surgeon rapidly assimilating themeasurement data. For example, the calculated measurement data on thelocation of applied load to a surface may have little or no meaning to asurgeon. Conversely, an image of the surface being loaded with a contactpoint displayed on the surface can be rapidly assimilated by the surgeonto determine if there is an issue with the contact point.

In one embodiment, shoulder joint system 160 transmits and receivesinformation wirelessly. Wireless operation reduces clutter within thesurgical area, wired distortion of, or limitations on, measurementscaused by the potential for physical interference by, or limitationsimposed by, cables connecting a device with an internal power with datacollection, storage, or display equipment in an operating roomenvironment. Electronic circuitry 236 includes wireless communicationcircuitry 720. In one embodiment, wireless communication circuitry 720is configured for short range telemetry and battery operation.Typically, measurement device 154, and computer 162 are located in anoperating room such that the transmission of measurement data frommeasurement device 156 to computer 162 is less than 10 meters. Asillustrated, the exemplary communications system comprises wirelesscommunication circuitry 720 of measurement device 154 and receivingsystem wireless communication circuitry 722 of computer 162. Wirelesscommunications circuitry 720 comprises, but is not limited to, theantenna 360, a matching network 716, the telemetry transceiver 714, aCRC circuit 712, a data packetizer 710, and a data input 708. Wirelesscommunication circuitry 720 can include more or less than the number ofcomponents shown and are not limited to those shown or the order of thecomponents.

Similarly, computer 162 includes wireless communication circuitry 722.Wireless communication circuitry 722 comprises an antenna 724, amatching network 726, a telemetry receiver 728, a CRC circuit 730, and adata packetizer 732. Notably, other interface systems can be directlycoupled to the data packetizer 732 for processing and rendering sensordata. In general, electronic circuitry 236 couples to sensors 230 and isconfigured to transmit quantitative measurement data to computer 162 inreal-time to process, display, analyze, and provide feedback.Measurement device 154 includes a plurality of load sensors configuredto measure loads applied to external curved surface 224. Measurementdevice 154 further includes an inertial measurement unit comprising oneor more inertial sensors and other parameter measurement sensors aslisted herein above. The measurement data from the plurality of loadsensors and the inertial sensors is transmitted to computer 162.Computer 162 can calculate a load magnitude applied to external curvedsurface 224 from the plurality of load sensors. In the example, threeload sensors are used for the measurement. Computer 162 can furthercalculate a position of applied load (contact point) to external curvedsurface 224 of measurement device 154. Measurement device 154 canfurther use measurement data from position measurement system 742 tomonitor position and movement of measurement device 154 or a prostheticcomponent. The position or tracking data from position measurementsystem 742 is also sent to computer 162. The results can also bedisplayed on display 164 of computer 162. In one embodiment, measurementdata from position measurement system 742 can be used to measure rangeof motion, alignment, and impingement. In one embodiment, thetransmission of the measurement data from different sensors orcomponents can be sent on different channels or the measurement data canbe sent at different times on the same channel.

As mentioned previously, wireless communication circuitry comprises datainput 708, data packetizer 710, CRC circuit 712 telemetry transmitter714, matching network 716, and antenna 718. In general, measurement datafrom sensors 230 is provided to data input 708 of wireless communicationcircuitry 720. In one embodiment, the measurement data from sensors 230can come directly from interface circuitry 706, from memory 704, fromcontrol logic 702, or from a combination of paths to data input 708. Inone embodiment, measurement data can be stored in memory 704 prior tobeing provided to data input 708. Data packetizer 710 assembles themeasurement data into packets and includes sensor information receivedor processed by control logic 702. Control logic 702 can comprisespecific modules for efficiently performing core signal processingfunctions of the measurement device 154. Control logic 702 provides thefurther benefit of reducing the form factor to meet dimensionalrequirements for integration into measurement device 154.

In general, measurement data from measurement device 154 is encrypted.In one embodiment, the output of data packetizer 710 couples to theinput of CRC circuit 712. CRC circuit 712 applies error code detectionon the packet data. The cyclic redundancy check is based on an algorithmthat computes a checksum for a data stream or packet of any length.These checksums can be used to detect interference or accidentalalteration of data during transmission. Cyclic redundancy checks areespecially good at detecting errors caused by electrical noise andtherefore enable robust protection against improper processing ofcorrupted data in environments having high levels of electromagneticactivity. The output of CRC circuit 712 couples to the input oftelemetry transceiver 714. The telemetry transceiver 714 then transmitsthe CRC encoded data packet through the matching network 716 by way ofthe antenna 360. Telemetry transceiver 714 can increase a carrierfrequency in one or more steps and add the information or measurementdata from measurement device 154 to the carrier frequency. The matchingnetwork 716 provides an impedance match for achieving optimalcommunication power efficiency between telemetry transmitter 714 andantenna 360.

Antenna 360 can be integrated with components of the measurement device154 to provide the radio frequency transmission. The substrate for theantenna 360 and electrical connections with the electronic circuitry 236can further include the matching network 716. In one embodiment, theantenna 360 and a portion of the matching network 716 can be a wire orformed in printed circuit board 234 that interconnects the componentsthat comprise electronic circuitry 236. This level of integration of theantenna and electronics enables reductions in the size and cost ofwireless equipment. Potential applications may include, but are notlimited to any type musculoskeletal equipment or prosthetic componentswhere a compact antenna can be used. This includes disposable modules ordevices as well as reusable modules or devices and modules or devicesfor long-term use.

The process for receiving wireless communication circuitry 722 is theopposite of the sending process. Antenna 724 receives transmittedmeasurement data from wireless communication circuitry 720 Wirelesscommunication circuitry 720 can transmit at low power such thatreceiving wireless communication circuitry 722 must be in proximity, forexample within 10 meters to receive measurement data. Antenna 724couples to matching network 726 that efficiently couples the measurementdata to telemetry transmitter circuit 728. The measurement data can besent on a carrier signal that supports wireless transmission. Themeasurement data is stripped off from the carrier signal by telemetrytransmitter 728. The measurement data is received by CRC circuit 730from telemetry transmitter 728. CRC circuit 730 performs a cyclicredundancy check algorithm to verify that the measurement data has notbeen corrupted during transmission. The CRC circuit 730 provides thechecked measurement data to data packetizer 732. Data packetizer 732reassembles the measurement data where it is provided to USB interface734. USB interface 734 provides the measurement data to computer 162 forfurther processing.

It should be noted that the measuring, transmitting, receiving, andprocessing of the measurement data can be performed in real-time for useby a surgeon to support installation of a shoulder joint. In oneembodiment, computer 162 displays at least a portion of one prostheticcomponent. In the example, external curved surface 224 and rim 242 ofmeasurement device 154 is displayed on display 164 coupled to computer162. Measurement data from sensors 230 and position measurement system742 is used to calculate a load magnitude and a position of applied loadon external curved surface 224 of measurement device 154. The locationof each load sensor is known relative to external curved surface 224.The position of applied load can be calculated using the locationinformation from each load sensor and the load magnitude at eachlocation by computer 162 as disclosed in detail herein above. Theposition of applied load is also called contact point 382 on GUI 380 ofdisplay 164. Similarly, the load magnitude at contact point 382 can becalculated from the three load sensors and the three load sensorlocations. Typically, the shoulder joint is moved through a predeterminerange of motion. The minimum load, the maximum load, and the load at thecurrent location is displayed on GUI 380 respectively in display boxes380, 390, and 386. The amount of rotation or range of motion can also beindicated. These measurements are measured or calculated in real-time.Rim 242 can also be highlighted to indicate impingement during thepredetermined range of motion. In one embodiment, rim 242 will highlight an area of rim 242 in proximity to the measured impingement.Adjustments can be performed that affect alignment, loading, position ofload, rotation, or other parameters and monitored in real-time ondisplay 164. The adjustments can support optimization after the measuredparameters are within specification to fine tune the prostheticcomponent installation with quantitative measurement data.

FIG. 33 is a block diagram of the system or computer in accordance withan example embodiment. The exemplary diagrammatic representation of amachine, system, or computer in the form of a system 800 within which aset of instructions, when executed, may cause the machine to perform anyone or more of the methodologies discussed above. In some embodiments,the machine operates as a standalone device. In some embodiments, themachine may be connected (e.g., using a network) to other machines. In anetworked deployment, the machine may operate in the capacity of aserver or a client user machine in server-client user networkenvironment, or as a peer machine in a peer-to-peer (or distributed)network environment.

The machine may comprise a server computer, a client user computer, apersonal computer (PC), a tablet PC, a laptop computer, a desktopcomputer, a control system, logic circuitry, a sensor system, an ASIC,an integrated circuit, a network router, switch or bridge, or anymachine capable of executing a set of instructions (sequential orotherwise) that specify actions to be taken by that machine. It will beunderstood that a device of the present disclosure includes broadly anyelectronic device that provides voice, video or data communication.Further, while a single machine is illustrated, the term “machine” shallalso be taken to include any collection of machines that individually orjointly execute a set (or multiple sets) of instructions to perform anyone or more of the methodologies discussed herein.

System 800 may include a processor 802 (e.g., a central processing unit(CPU), a graphics processing unit (GPU, or both), a main memory 804 anda static memory 806, which communicate with each other via a bus 808.System 800 may further include a video display unit 810 (e.g., a liquidcrystal display (LCD), a flat panel, a solid state display, or a cathoderay tube (CRT)). System 800 may include an input device 812 (e.g., akeyboard), a cursor control device 814 (e.g., a mouse), a disk driveunit 816, a signal generation device 818 (e.g., a speaker or remotecontrol) and a network interface device 820.

The disk drive unit 816 can be other types of memory such as flashmemory and may include a machine-readable medium 822 on which is storedone or more sets of instructions 824 (e.g., software) embodying any oneor more of the methodologies or functions described herein, includingthose methods illustrated above. Instructions 824 may also reside,completely or at least partially, within the main memory 804, the staticmemory 806, and/or within the processor 802 during execution thereof bythe system 800. Main memory 804 and the processor 802 also mayconstitute machine-readable media.

Dedicated hardware implementations including, but not limited to,application specific integrated circuits, programmable logic arrays andother hardware devices can likewise be constructed to implement themethods described herein. Applications that may include the apparatusand systems of various embodiments broadly include a variety ofelectronic and computer systems. Some embodiments implement functions intwo or more specific interconnected hardware modules or devices withrelated control and data signals communicated between and through themodules, or as portions of an application-specific integrated circuit.Thus, the example system is applicable to software, firmware, andhardware implementations.

In accordance with various embodiments of the present disclosure, themethods described herein are intended for operation as software programsrunning on a computer processor. Furthermore, software implementationscan include, but not limited to, distributed processing orcomponent/object distributed processing, parallel processing, or virtualmachine processing can also be constructed to implement the methodsdescribed herein.

The present disclosure contemplates a machine readable medium containinginstructions 824, or that which receives and executes instructions 824from a propagated signal so that a device connected to a networkenvironment 820 can send or receive voice, video or data, and tocommunicate over the network 826 using the instructions 824. Theinstructions 824 may further be transmitted or received over the network826 via the network interface device 820.

While the machine-readable medium 822 is shown in an example embodimentto be a single medium, the term “machine-readable medium” should betaken to include a single medium or multiple media (e.g., a centralizedor distributed database, and/or associated caches and servers) thatstore the one or more sets of instructions. The term “machine-readablemedium” shall also be taken to include any medium that is capable ofstoring, encoding or carrying a set of instructions for execution by themachine and that cause the machine to perform any one or more of themethodologies of the present disclosure.

The term “machine-readable medium” shall accordingly be taken toinclude, but not be limited to: solid-state memories such as a memorycard or other package that houses one or more read-only (non-volatile)memories, random access memories, or other re-writable (volatile)memories; magneto-optical or optical medium such as a disk or tape; andcarrier wave signals such as a signal embodying computer instructions ina transmission medium; and/or a digital file attachment to e-mail orother self-contained information archive or set of archives isconsidered a distribution medium equivalent to a tangible storagemedium. Accordingly, the disclosure is considered to include any one ormore of a machine-readable medium or a distribution medium, as listedherein and including art-recognized equivalents and successor media, inwhich the software implementations herein are stored.

Although the present specification describes components and functionsimplemented in the embodiments with reference to particular standardsand protocols, the disclosure is not limited to such standards andprotocols. Each of the standards for Internet and other packet switchednetwork transmission (e.g., TCP/IP, UDP/IP, HTML, HTTP) representexamples of the state of the art. Such standards are periodicallysuperseded by faster or more efficient equivalents having essentiallythe same functions. Accordingly, replacement standards and protocolshaving the same functions are considered equivalents.

FIG. 34 is an illustration of a communication network 900 formeasurement and reporting in accordance with an exemplary embodiment.Briefly, the communication network 900 expands broad data connectivityto other devices or services. As illustrated, the measurement andreporting system 902 can be communicatively coupled to thecommunications network 900 and any associated systems or services.

As one example, measurement system 902 can share its parameters ofinterest (e.g., angles, load, balance, distance, alignment,displacement, movement, rotation, and acceleration) with remote servicesor providers, for instance, to analyze or report on surgical status oroutcome. This data can be shared for example with a service provider tomonitor progress or with plan administrators for surgical monitoringpurposes or efficacy studies. The communication network 900 can furtherbe tied to an Electronic Medical Records (EMR) system to implementhealth information technology practices. In other embodiments, thecommunication network 900 can be communicatively coupled to HIS HospitalInformation System, HIT Hospital Information Technology and HIM HospitalInformation Management, EHR Electronic Health Record, CPOE ComputerizedPhysician Order Entry, and CDSS Computerized Decision Support Systems.This provides the ability of different information technology systemsand software applications to communicate, to exchange data accurately,effectively, and consistently, and to use the exchanged data.

The communications network 900 can provide wired or wirelessconnectivity over a Local Area Network (LAN) 904, a Wireless Local AreaNetwork (WLAN) 910, a Cellular Network 906, and/or other radio frequency(RF) system (see FIG. 4 ). The LAN 904 and WLAN 910 can becommunicatively coupled to the Internet 908, for example, through acentral office. The central office can house common network switchingequipment for distributing telecommunication services. Telecommunicationservices can include traditional POTS (Plain Old Telephone Service) andbroadband services such as cable, HDTV, DSL, VoIP (Voice over InternetProtocol), IPTV (Internet Protocol Television), Internet services, andso on.

The communication network 900 can utilize common computing andcommunications technologies to support circuit-switched and/orpacket-switched communications. Each of the standards for Internet 908and other packet switched network transmission (e.g., TCP/IP, UDP/IP,HTML, HTTP, RTP, MMS, SMS) represent examples of the state of the art.Such standards are periodically superseded by faster or more efficientequivalents having essentially the same functions. Accordingly,replacement standards and protocols having the same functions areconsidered equivalent.

The cellular network 906 can support voice and data services over anumber of access technologies such as GSM-GPRS, EDGE, CDMA, UMTS, WiMAX,2G, 3G, WAP, software defined radio (SDR), and other known technologies.The cellular network 906 can be coupled to base receiver 912 under afrequency-reuse plan for communicating with mobile devices 914.

The base receiver 912, in turn, can connect the mobile device 914 to theInternet 908 over a packet switched link. The internet 908 can supportapplication services and service layers for distributing data from themeasurement system 902 to the mobile device 914. Mobile device 914 canalso connect to other communication devices through the Internet 908using a wireless communication channel. The mobile device 914 can alsoconnect to the Internet 908 over the WLAN 910. Wireless Local AccessNetworks (WLANs) provide wireless access within a local geographicalarea. WLANs are typically composed of a cluster of Access Points (APs)916 also known as base stations. The measurement system 902 cancommunicate with other WLAN stations such as laptop 918 within the basestation area. In typical WLAN implementations, the physical layer uses avariety of technologies such as 802.11b or 802.11g WLAN technologies.The physical layer may use infrared, frequency hopping spread spectrumin the 2.4 GHz Band, direct sequence spread spectrum in the 2.4 GHzBand, or other access technologies, for example, in the 5.8 GHz ISM bandor higher ISM bands (e.g., 24 GHz, etcetera).

By way of the communication network 900, the measurement system 902 canestablish connections with a remote server 920 on the network and withother mobile devices for exchanging data. The remote server 920 can haveaccess to a database 922 that is stored locally or remotely and whichcan contain application specific data. The remote server 920 can alsohost application services directly, or over the internet 908.

FIG. 35 is a diagram of a robot 1000 supporting installation of ashoulder joint in accordance with an example embodiment. In general, arobot can support or assist in the installation of the shoulder jointunder control of a surgeon. In the example embodiment, measurementdevice 154 can be coupled to robot 1000. One example of the robot is theRobodoc surgical robot with a robotic assisted joint installationapplication. Robot 1000 can also include surgical CNC robots, surgicalhaptic robots, surgical tele-operative robots, surgical hand-heldrobots, or any other surgical robot. Measurement device 154 can beautomated to couple to and work with robot 1000 thereby replacing directhand control by the surgeon. The actions taken by robot 1000 in controlof measurement device 154 can be smoother and more accurate by havingrobot 1000 use the measurement data in real-time and providing feedbackto measurement device 154 for subsequent steps. An added benefit can beshortening the time of surgery that reduces the time a patient is underanesthesia.

Robot 1000 can be configured to perform computer-assisted surgery andmore specifically shoulder surgery with measurement device 154.Typically, robot 1000 and measurement device 154 is used forcomputer-assisted surgery to improve performance, alignment, stability,range of motion, reduce surgical time, and minimize impingement in theinstallation of a prosthetic joint and more specifically a shoulderjoint. In one embodiment, robot 1000 can distract, perform bone cuts,align prosthetic components, reposition prosthetic components, adjustloading, perform tissue releases, perform range of motion, improvestability using the real-time measurement data sent from measurementdevice 154.

In general, measurement data from measurement device 154 can bewirelessly transmitted to a computer of robot 1000. Alternatively, themeasurement data can be hard wired to robot 1000. Examples ofmeasurement data from measurement device 154 can be range of motion forpredetermined movements, impingement, load magnitude, position of load,position, and motion to name but a few. The measurement data received byrobot 1000 can be further processed to calculate and display measurementdata needed by the surgeon for the preparation of the bone surfaces orinstallation of the final prosthetic components based on thequantitative measurement data. The prepared bone surfaces will receive aprosthetic component that supports proper alignment for optimal range ofmotion and stability. In one embodiment, the computer in robot 1000includes one or more algorithms that are used at various stages of thesurgery. The measurement data from measurement device 154 is input tothe algorithms of robot 1000 and the algorithms can convert the datainto information displayed on the display for robotic actions that areused to make bone cuts, pin placements, prosthetic component sizing,etcetera or provide feedback on actions that the surgeon may take. Thefeedback may take the form of audible, visual, or haptic feedback thatguides the surgeon on the distraction or subsequent steps taken by therobot to support or resist an action based on the measurement data. Thefeedback can also smooth or prevent motions by a user that could bedetrimental to the surgery. Furthermore, the status of the measurementdata can be used to generate a workflow that is subsequently implementedby a surgeon or automatically by robot 1000 to enhance performance andreliability of the shoulder joint installation.

FIG. 36 is an illustration of a measurement device 1100 in accordancewith an example embodiment. Measurement device 1100 houses electroniccircuitry and at least one sensor identical to measurement device 154 asshown in FIGS. 3-21 . Measurement device 1100 transmits measurement datato a computer in proximity to display measurement data in real-time.Measurement data from measurement device 1100 can be provided on a GUI380 as shown in FIG. 22A-FIG. 27A as disclosed herein above. In theexample, measurement device 1100 is configured for a shoulder implant.In general, measurement device 1100 can be adapted for use in themusculoskeletal system such as bones, tissue, ligaments, tendons, orjoints. As shown, measurement device 1100 is configured to couple to ahumeral prosthesis for measuring range of motion, stability,impingement, load, and position of load of the shoulder joint. A glenoidsphere of the shoulder joint is configured to couple to an externalcurved surface 1104 of measurement device 1100. Moreover, embodiments oruses stated for measurement device 154 herein above can be applied tomeasurement device 1100.

Measurement device 1100 comprises an upper housing 1106 and a bottomhousing 1108. Upper housing 1106 and bottom housing 1108 couple togetherto form a hermetically sealed enclosure that houses the electroniccircuitry, power source, and sensors. Upper housing 1106 has a rim 1102and external curved surface 1104. Measurement device 1100 furtherincludes a shim 1110 configured to couple to bottom housing 1108. Shim1110 is a removable structure of measurement device 1110 that isconfigured to couple to a humeral tray of the humeral prosthesis. Aplurality of shims are provided with measurement device 1100 to change aheight of measurement device 1100. In one embodiment, increasing theheight of measurement device 1100 using a shim can be used to increaseloading applied by the muscles, tendons, or ligaments of the shoulderjoint. Conversely, decreasing the height of the measurement device 1100using a shim of a lessor height can decrease loading applied by themuscles, tendons, or ligaments of the shoulder joint. In one embodiment,a plurality of shims can be provided that change an angle thatmeasurement device 1100 presents to the glenoid sphere when coupled inthe shoulder joint.

FIG. 37A is a superior view of measurement device 1100 in accordancewith an example embodiment. As mentioned previously, shim 1110 removablycouples to bottom housing 1108. This allows different shims to berapidly coupled to or removed from measurement device 1100 during ashoulder joint installation to determine an optimal fit or placement ofthe humeral prosthesis in the shoulder joint using quantitativemeasurement data. A cut out 1112 is shown in bottom housing 1108. In oneembodiment, a ledge or protrusion is formed on bottom housing 1108 thatunderlies retaining feature 1114. Retaining feature 1114 is a tabextending from shim 1110. In one embodiment, retaining feature 1114couples to the ledge or protrusion of bottom housing 1108 under force toretain shim 1110 to bottom housing 1108. In one embodiment, retainingfeature 1114 is flexible such that retaining feature 1114 can be forcedaway from the ledge or protrusion of bottom housing 1108 to release shim1110 from bottom housing 1108. Cutout 1112 in bottom housing 1108 allowsaccess to facilitate flexing of retaining feature 1114 away from bottomhousing 1108.

FIG. 37B is a view of measurement device 1100 illustrating externalcurved surface 1104 in accordance with an example embodiment. Ingeneral, upper housing 1106 of measurement device 1100 includes rim 1102and external curved surface 1104. As mentioned previously, a glenoidsphere couples of the shoulder joint couples to external curved surface1104 of measurement device 1100. In one embodiment, the plurality ofsensors underlie external curved surface 1104 and are configured tomeasure a force, pressure, or load applied at each location where asensor is placed. The measurement data from the plurality of sensors isprovided to a computer to calculate a load magnitude applied to externalcurved surface 1104 by the glenoid sphere of the shoulder joint and thelocation of the applied load by the glenoid sphere.

FIG. 37C is a side view of measurement device 1100 in accordance with anexample embodiment. Upper housing 1106 is coupled to bottom housing1108. Shim 1110 is coupled to bottom housing 1108. The side viewillustrates under-cut 1116 and under-cut 1118 in shim 1110. In oneembodiment, under-cut 1118 is also on the opposing side of shim 1110.Under-cuts 1116 and 1118 are used to retain and align measurement device1100 to an implant tray of the humeral prosthesis. In one embodiment,corresponding features formed in the implant tray couple to under-cuts1116 and 1118.

FIG. 37D is an anterior view of measurement device 1100 illustratingunder-cut 1118 formed in shim 1110 in accordance with an exampleembodiment. Under-cut 1118 is used to retain and align measurementdevice 1110 to the implant tray of the humeral prosthesis.

FIG. 38 is an exploded view of measurement device 1100 in accordancewith an example embodiment. A flexible interconnect 1120 is configuredto couple a plurality of sensors to electronic circuitry 1130. Theplurality of sensors can be formed in or on flexible interconnect 1120.In one embodiment, the plurality of sensors comprises a sensor 1122, asensor 1124, and a sensor 1126. In one embodiment, sensors 1122, 1124,and 1126 are formed in flexible interconnect 1120. Alternatively,sensors can be coupled to flexible interconnect 1120. In one embodiment,one or more reference sensors are formed in flexible interconnect 1120.In one embodiment, sensors 1122, 1124, and 1126 and interconnect inflexible interconnect 1120 are shielded. Sensors 1122, 1124, and 1126are configured to couple to external curved surface 1104.

Electronic components and power source 1132 are coupled to a printedcircuit board 1128. Printed circuit board 1128 includes one or morelevels of interconnect to connect the electronic components to formelectronic circuitry 1130 that is configured to control a measurementprocess and transmit measurement data. In one embodiment, power source1132 comprises batteries for powering measurement device 1100. Printedcircuit board 1128 can be a rigid printed circuit board that includes aconnector for coupling to flexible interconnect 1120. Electroniccircuitry 1130, flexible interconnect 1120, and sensors 1122, 1124, and1126 are placed in a cavity 1136 of bottom housing 1108. Upper housing1106 couples to bottom housing 1108 to form a housing for electroniccircuitry 1130, flexible interconnect 1120, and sensors 1122, 1124, and1126. In one embodiment, sensors 1122, 1124, and 1126 are placed atpredetermined locations between upper housing 1106 and bottom housing1108 to support a load magnitude and position of applied loadmeasurement where a glenoid sphere couples to external curved surface1104 of measurement device 1100 for the shoulder joint. As mentionedpreviously, the electronic circuitry 1130, the reference sensor, aposition measurement system (e.g. IMU), and sensors 1122, 1124, and 1126operate similarly to that described for measurement device 154 (see FIG.3 ) and will not be disclosed in detail for brevity. Furthermore,measurement device 1100 will transmit measurement data to computer 162and have measurement data displayed on display 164 as disclosed hereinabove. The measurement data can be displayed on GUI 380 in graphicalform to speed assimilation of the measurement data in the same manner asdiscussed for measurement device 154.

A shim 1110 couples to bottom housing 1108 to add height to measurementdevice 1100. A plurality of shims are provided with measurement device1100 where each shim of the plurality of shims has a differentthickness. Thus, shim 1110 can be removed and replaced with one of theother shims from the plurality of shims to change the height ofmeasurement device 1100 by a predetermined amount. Upper housing 1106,bottom housing 1108, and shim 1110 can be formed from a biologicalcompatible material such as a composite material, a polymer, plastic,metal, or a metal alloy. In one embodiment, upper housing 1106, bottomhousing 1108, and shim 1110 can be molded or 3D printed from a polymermaterial.

An implant tray 1134 is a component of the humeral prosthesis. In oneembodiment, implant tray 1134 couples to the humeral prosthesis. In oneembodiment, implant tray 1134 is held in place to the humeral prosthesisby a screw and implant tray 1134 can be removed by removing the screw.Shim 1110 is configured to couple to implant tray 1134 to holdmeasurement device 1100 in place for generating quantitative measurementdata related to the shoulder joint for assessing range of motion,stability, impingement, movement, load, or position of load.

FIG. 39 is a view of cavity 1136 of bottom housing 1108 of measurementdevice 1100 in accordance with an example embodiment. In the example,placement of components of measurement device 1100 are illustrated.Printed circuit board 1128 with the electronic components is coupled toan interior surface of bottom housing 1108. Printed circuit board 1148fits within cavity 1136 and is retained by printed circuit board snaps1142. Printed circuit board snaps 1142 are forced through openings inprinted circuit board 1128 to form an interference fit that preventsmovement and aligns printed circuit board 1128 within cavity 1136. Inone embodiment, printed circuit board snaps 1142 extend from theinterior surface of bottom housing 1108 and the heads of printed circuitboard snaps 1142 are made larger than the openings in printed circuitboard 1128. Printed circuit board 1128 has a connector 1146 that couplesto flexible interconnect 1120. In one embodiment, power source 1132couples to and is retained by printed circuit board 1128. Power source1132 provides power for electronic circuitry 1130 and sensors 1122,1124, and 1126 to provide measurement data for a complete shoulderreplacement surgery.

Sensors 1122, 1124, and 1126 couple to a surface 1144 on bottom housing1108 at predetermined locations relative to external surface 1104 ofupper housing 1106 (see FIG. 36 ). In one embodiment, sensors 1122,1124, and 1126 are located on a radial position of external curvedsurface 1106. In one embodiment, sensors 1122, 1124, and 1126 are spacedequidistant from one another. In one embodiment, a reference sensor 1148can be located centrally on or in flexible interconnect 1120 relative tosensors 1122, 1124, and 1126. Alternatively, more than one referencesensor can be formed on or in flexible interconnect 1120. Sensors 1122,1124, and 1126 are held in place by sensors snaps 1140. Sensor snaps1140 couple through openings in proximity to sensors 1122, 1124, and1126 to align and retain sensors 1122, 1124, and 1126 at thepredetermined locations. In one embodiment, a raised region is formedunderlying sensors 1122, 1124, and 1126. The raised regions extend abovesurface 1144 and provide a planar surface to support sensors 1122, 1124,and 1126.

FIG. 40 is a cross-sectional view of measurement device 1100 inaccordance with an example embodiment. Upper housing 1104 is showncoupling to bottom housing 1108. In one embodiment, a peripheral groove1152 is formed circumferentially on bottom housing 1108. A peripheraltongue 1150 is formed circumferentially on upper housing 1106 and isconfigured to couple to peripheral groove 1152 on bottom housing 1108.In one embodiment, glue or an adhesive can be used in peripheral groove1152 to seal and retain upper housing 1106 to bottom housing 1108.Alternatively, one or more retaining structures on upper housing 1106and one or more corresponding retaining structures on bottom housing1108 can be used to couple upper housing 1106 to bottom housing 1108.Peripheral tongue 1150 can comprise a conformal material that forms aseal when upper housing 1106 couples to bottom housing 1108.

Retaining feature 1114 on a superior side of measurement device 1100 isshown coupling shim 1110 to bottom housing 1108. Although not shownthere can be more than one retaining feature coupling shim 1110 tobottom housing 1110. Bottom housing 1108 has a cutout 1156 configured toreceive retaining feature 1114. Retaining feature 1114 has acorresponding protrusion 1154 configured to fit in cutout 1156. Asmentioned previously, retaining feature 1114 is flexible and can beflexed away from bottom housing 1108 such that protrusion 1154 isoutside cutout 1156 allowing shim 1110 to be removed from bottom housing1108.

Printed circuit board 1130 is retained to or in proximity to theinterior surface of bottom housing 1108. Flexible interconnect 1120 isshown coupling to connector 1146 on printed circuit board 1130. Sensor1122 formed in or placed on flexible interconnect is coupled betweenupper housing 1106 and bottom housing 1108. In one embodiment, sensor1122 couples to planar surfaces formed on an interior surface of upperhousing 1106 and the interior surface of bottom housing 1108. Sensor1122 underlies a predetermined location of external surface 1104. Thepredetermined locations of sensors 1122, 1124, and 1126 are used tocalculate a position of applied load and a load magnitude from themeasurement data. Note that flexible interconnect 1120 does not undergoany bends that kink the interconnect. Sensor snap 1140 is shown couplingthrough flexible interconnect 1120 to retain sensor 1120 at thepredetermined location.

FIGS. 41A and 41B illustrates measurement device 1100 with two differentshims in accordance with an example embodiment. In general, measurementdevice 1100 includes a plurality of shims. In the example, two differentshims are disclosed but more than two can be provided. Shim 1110 is azero height shim and corresponds to measurement device 1100 at a minimumheight. In the example, upper housing 1106 and bottom housing 1108 arecoupled together and configured to measure at least one parameter. Shim1110 is a separate component that couples to bottom housing 1108.Measurement device 1100 is shown with shim 1100 coupled to bottomhousing 1110 to form measurement device 1110 at a standard, normal orminimum height.

Shim 1160 is a 2.5 millimeter shim that raises the height of measurementdevice 1100 2.5 millimeters when compared to zero height shim 1100 ofFIG. 41A. In the example, upper housing 1106 and bottom housing 1108 arecoupled together and configured to measure at least one parameter. Shim1160 is a separate component that couples to bottom housing 1108.Measurement device 1100 is shown with shim 1160 coupled to bottomhousing 1110 to form measurement device 1110 at a height increased by2.5 millimeters. As stated previously, measurement device 1100 can beprovided with more than two shims of different heights. For example, theshoulder joint when reduced with shim 1110 of FIG. 41A might have aloading when measured by measurement device 1100 that is less thandesirable. Shim 1110 can then be removed and replaced with shim 1160.Reducing the shoulder joint with shim 1160 in measurement device 1160will increase tension on muscles of the shoulder joint therebyincreasing the loading applied to measurement device 1100. The tensionon the different muscles, ligaments, or tendons can be adjusted toachieve stability, maximize range of motion, minimize impingement, andload the shoulder joint within an acceptable range based on quantitativemeasurement data. For example, the tension can be adjusted using softtissue tensioning to adjust the loading within the acceptable rangemeasured by load sensors within measurement device 1100 in real-time.

FIG. 42 is a cross-sectional view of external curved surface 1104 ofupper housing 1106 that is modified to direct loading to predeterminedareas of external curved surface 1104 in accordance with an exampleembodiment. The cross-sectional view shows upper housing 1106 coupled tobottom housing 1108 to form an enclosure to isolate and hermeticallyseal electronic circuitry 1130, flexible interconnect, 1120, and sensors1122, 1124, and 1126 from an external environment. Shim 1110 couples tobottom housing 1108. A partial view of glenoid sphere 1194 is showncoupling to external curved surface 1104 of upper housing 1106. Ingeneral, loading by glenoid sphere 1194 is directed to the plurality ofload sensors underlying external curved surface 1104. In the example,the loading is directed to sensor 1122, sensor 1124, and sensor 1126(not shown in the illustration). As shown, sensors 1122 and 1124respectively underlie region 1172 and region 1174 of external curvedsurface of 1104. Similarly, sensor 1126 will underlie region 1176 ofFIG. 42 . As previously mentioned, sensors 1122, 1124, and 1126 arelocated at predetermined radial positions of external curved surface1104. In one embodiment, sensors 1122, 1124, and 1126 are also spacedequidistant from each other. Sensors 1122, 1124, and 1126 are placed asclose to rim 1102 of upper housing 1106 as feasible to maximize themeasurement area on external curved surface 1104.

In the example, glenoid sphere 1194 is 38 millimeters in diameter andhas a 19 millimeter radius. In one embodiment, external curved surface1104 has a larger radius than glenoid sphere 1194. In the example, theradius of external curved surface is 38.15 millimeters. External curvedsurface 1104 is modified such that glenoid sphere 1194 only couples toregions 1172, 1174, and 1176 of external curved surface 1104. Sensors1122, 1124, and 1126 respectively underlie regions 1172, 1174, and 1176of external curved surface 1104. Thus, loading applied by glenoid sphere1194 is directed to sensors 1122, 1124, and 1126 of measurement device1100 and not to areas of external curved surface 1104 outside regions1172, 1174, and 1176. In general, there are two regions on externalcurved surface 1104 that does not couple to glenoid sphere 1194. In oneembodiment, a region 1192 of external curved surface 1104 of upperhousing 1106 does not couple to glenoid sphere 1194. Note that a gap isshown between glenoid sphere 1194 and external curved surface 1104 inregion 1192. Region 1192 corresponds to a load measurement area betweensensors 1122, 1124, and 1126. In one embodiment, the gap between glenoidsphere 1194 and external curved surface 1104 in region 1192 isapproximately 0.15 millimeters. In one embodiment, region 1192 can bemolded having a 0.15 millimeter cutout in region 1192. Alternatively,0.15 millimeter of material can be removed from region 1192.

In one embodiment, a region 1190 of external curved surface 1104 ofupper housing 1106 does not couple to glenoid sphere 1194. Note that agap is shown between glenoid sphere 1194 and external curved surface1104 in region 1130. Region 1190 corresponds to the area outside region1192 and regions 1172, 1174, and 1176 of external curved surface 1104.In one embodiment, the gap between glenoid sphere 1194 and externalcurved surface 1104 in region 1190 is approximately 0.10 millimeters. Inone embodiment, can be molded having a 0.10 millimeter cutout in region1190. Alternatively, 0.10 millimeter of material can be removed fromregion 1190.

FIG. 43 is a block diagram of loading measurement device 1100 inaccordance with an example embodiment. The method will refer tocomponents listed in FIG. 42 . In a step 1180, a glenoid sphere 1194 ofa shoulder joint loads measurement device 1100. In the example, theglenoid sphere 1194 couples to the scapula and measurement device 1100couples to the humeral prosthesis to form the shoulder joint. In a step1182, glenoid sphere 1194 couples to regions 1172, 1174, and 1176directly. Sensors 1122, 1124, and 1126 respectively underlie regions1172, 1174, and 1176 of external curved surface 1104 of upper housing1106. In one embodiment, glenoid sphere 1194 does not couple to regions1190 and 1192 of external curved surface 1104 of upper housing 1106.Loading applied by glenoid sphere 1194 is coupled through anddistributed among sensors 1122, 1124, and 1126. In a step 1186, bydistributing the load through regions 1172, 1174, and 1176 and therebythrough sensors 1122, 1124, and 1126 the expected sensitivity of thesensors is correct. In one embodiment, loading applied by glenoid sphere1194 to measurement device 1100 only couples through sensors 1122, 1124,and 1126.

FIG. 44 is an illustration of measurement device 1100 illustratingdifferent regions of external curved surface 1104 of upper housing 1106in accordance with an example embodiment. In general, external curvedsurface 1104 has three different regions each having a different surfaceheight. The first regions corresponds to locations of the sensors formeasuring a force, pressure, or load applied to external curved surface1104. The surface height and curvature of the first regions correspondsto a radius configured to receive a spherical prosthetic component. Inthe example, the glenoid sphere has a radius of 19 millimeters and theradius of the first regions corresponding to the locations of thesensors is 19.075 millimeters. In one embodiment, external curvedsurface 1104 has a larger radius than spherical prosthetic componentthat couples to it.

The second region of external curved surface 1104 corresponds to alocation of applied load of the spherical prosthetic component toexternal curved surface 1104. In general, the sensors are locatedadjacent to or in proximity to rim 1102 of upper housing 1106. Placingthe sensors in proximity to the rim 1102 maximizes area in which thesensors can accurately measure the location of applied load. In oneembodiment, the sensors are located on a radial position of externalcurved surface 1104. In one embodiment, the sensors are spacedequidistant from one another. In one embodiment, the second region canbe located at or below the sensor locations. In one embodiment, thesecond region can be an irregular shape. In one embodiment, the secondregion can comprise more than one second region. In the example, thesurface of the second region of external curved surface 1104 is belowthe surface of the first regions. In one embodiment, the sphericalprosthetic component does not couple to the second region when coupledto external curved surface 1104. The spherical prosthetic componentcouples to the first regions corresponding to the sensor locations.

The third region of external curved surface 1104 corresponds to alocation of applied load that is in proximity to the sensors or abovethe sensors on external curved surface 1104. In one embodiment, therange of motion of the spherical prosthetic component when coupled toexternal curved surface 1104 does not typically place the position ofapplied load near rim 1102 of upper housing 1106. In general, the thirdregion corresponds to extremes of the range of motion for the prostheticjoint. In one embodiment, the third region can be located in proximityto or above the sensor locations. In one embodiment, the third regioncan be an irregular shape. In one embodiment, the third region cancomprise more than one third region. In the example, the third region ofexternal curved surface 1104 is outside the second region of externalcurved surface 1104 but does not include the first regions. In oneembodiment, the spherical prosthetic component does not couple to thethird region when coupled to external curved surface 1104. The sphericalprosthetic component couples to the first regions corresponding to thesensor locations. In the example, the surface of the third region isbelow the surface of the first regions. In one embodiment, the surfaceof the second region is below the surface of the third region.

In the example, a circle 1196 is drawn on external curved surface 1104to define a boundary that identifies a region 1190 and a region 1192.Region 1192 corresponds to the second region of external curved surface1104 disclosed herein above. Region 1192 is an area of external curvedsurface 1104 that is within circle 1196. Region 1190 corresponds to thethird region of external curved surface 1104. In one embodiment, region1190 is an area of external curved surface 1104 that is outside ofcircle 1196 but does not include regions 1172, 1174, and 1176 up to rim1102. As mentioned previously, sensors 1122, 1124, and 1126 as shown inFIG. 39 respectively underlie regions 1172, 1174, and 1176. In oneembodiment, regions 1172, 1174, and 1174 have an area larger than orequal to an area of sensors 1122, 1124, and 1126. In one embodiment,regions 1172, 1174, and 1176 have a curved surface configured tointerface with glenoid sphere 1194 of FIG. 42 . In the example, regions1172, 1174, and 1176 have a curved surface corresponding to a radius of19.075 millimeters whereas the glenoid sphere has a radius of 19millimeters. A surface of region 1192 of external curved surface 1104 isbelow the surface of regions 1172, 1174, and 1176. In the example, thesurface of region 1192 is 0.15 millimeters below the surfaces of regions1172, 1174, and 1176 such that glenoid sphere 1194 of FIG. 42 does notcouple to region 1192 when glenoid sphere 1194 is coupled to measurementdevice 1100. A surface of region 1190 of external curved surface 1104 isbelow the surface of regions 1172, 1174, and 1176. In the example, thesurface of region 1190 is 0.10 millimeters below the surfaces of regions1172, 1174, and 1176 such that glenoid sphere 1194 does not couple toregion 1190 when glenoid sphere 1194 is coupled to measurement device1100. In the example, the surface of region 1190 is above the surface ofregion 1192 in relation to regions 1172, 1174, and 1176. In oneembodiment, having regions 1190, 1192, 1172, 1174, and 1176 of externalcurved surface 1104 directs loading applied by glenoid sphere 1194through sensors 1122, 1124, and 1126 which yields an expectedsensitivity for the measurement system.

Referring briefly to FIGS. 1-3 , a shoulder joint system 160 isdisclosed comprising a first shoulder prosthesis and a second shoulderprosthesis. In general, shoulder joint system 160 can be used for aprosthetic reverse shoulder or a normal prosthetic shoulder. Theelectronic circuitry and sensors can be housed in either a prostheticcomponent that couples to the humerus, a prosthetic component thatcouples to the scapula, or both. In one embodiment, the first shoulderprosthesis is a humeral prosthesis 158 configured to couple to humerus150. Humeral prosthesis 158 comprises a stem 124, a neck 126, and a tray156. In one embodiment, the second shoulder prosthesis is a glenoidsphere 152 configured to couple to scapula 140. Humeral prosthesis 158and glenoid sphere 152 each have external curved surfaces configured tomate together to support movement and rotation of the shoulder joint.Alternatively in normal prosthetic shoulder, the first shoulderprosthesis is a glenoid prosthesis 114 and the second shoulderprosthesis is a humeral prosthesis 102.

During a trialing process a humeral liner 128 of humeral prosthesis 158is removed and a measurement device 154 replaces humeral liner 128 totake one or more measurements to support installation of shoulder jointsystem 160. Measurement device 154 has an external curved surfaceconfigured to mate with glenoid sphere 152 and support movement of theshoulder joint system. In one embodiment, measurement device will bedimensionally identical to the humeral liner that couples to humeraltray 156. Referring briefly to FIGS. 5-21 , electronic circuitry and aplurality sensors are shown in measurement device 154. In particular,FIGS. 5 and 6 illustrate measurement device 154 having an upper housing220 and a bottom housing 222. Three sensors 230 are illustrated that arelocated at different radial locations beneath external curved surface224 of upper housing 220. Upper housing 220 couples to bottom housing222 to form a hermetic seal that houses the electronic circuitry and aplurality of sensors. In one embodiment, the hermetic seal is formed byan o-ring or adhesive that couples between upper housing 220 and bottomhousing 222. Referring briefly to FIG. 16 , one or more housing snaps279 are used to couple upper housing 220 to bottom housing 222 ofmeasurement device 154. In one embodiment, a housing snap 278 comprisesa protrusions formed on a sidewall 328 of bottom housing 222 and acorresponding opening formed on upper housing 220. The region of upperhousing 220 having the openings is configured to flex such that theupper housing 220 can be forcibly pressed onto bottom housing 222 untilthe opening overlies a corresponding housing snap 278. The one or morehousing snaps 278 preloads the plurality of sensors when coupling upperhousing 220 to bottom housing 222. Referring briefly to FIG. 29B aplurality of sensors are each located a radial position relative to theexternal curved surface of measurement device 154. In one embodiment 3sensors are located at 3 different radial locations. Referring brieflyto FIG. 31 , force sensors 530, 532, and 534 are oriented such that thereaction forces are directed to a center of rotation of a shoulderprosthesis. A block diagram of electronic circuitry 236 of measurementdevice 154 is disclosed in FIG. 32 . Electronic circuitry 236operatively couples to the plurality of sensors in measurement device154. Electronic circuitry 236 controls a measurement process andtransmits measurement data.

Referring briefly to FIG. 19 , a flexible interconnect 228 couples theplurality of sensors 230 to electronic circuitry 236. Referring brieflyto FIG. 14 , flexible interconnect 228 couples a support structure 262to place plurality of sensors 230 in position relative to the externalcurved surface of upper housing 220. In one embodiment, flexibleinterconnect 228 couples to an interior surface 244 of bottom housing222. In one embodiment, flexible interconnect 228 couples to supportstructure 262 a predetermined angle such that the surface of supportstructure 262 is non-parallel to interior surface 244 of bottom housing222. In one embodiment, support structure 262 positions plurality ofsensor 230 to couple between upper housing 220 and bottom housing 222.Each sensor of plurality of sensors 230 underlies the external curvedsurface of upper housing 220 at predetermined locations discussedherein. Each sensor of plurality of sensors 230 respectively couples toa planar surface on the interior of the upper housing and a planarsurface of the bottom housing. In one embodiment, the three load sensorsare placed equidistant from each other.

Electronic circuitry 236 and the plurality of sensors transmitmeasurement data to a computer 162 of FIG. 32 . Computer 162 isconfigured to receive the measurement data from the shoulder jointsystem that includes measurement device 154 but can include sensors inother components of the shoulder joint system. Electronic circuitry 236of the first shoulder prosthesis and computer 162 can be in two-waycommunication. In one embodiment, three load sensors are configured tomeasure loading applied to the first shoulder prosthesis. In oneembodiment, computer 162 is configured to calculate a force magnitudeand location of applied force using the measurements and locations ofthe first, second, and third sensors underlying the external curvedsurface of measurement device 154. In one embodiment, the force appliedto the external curved surface of measurement device 154 is normal tothe external curved surface. In one embodiment, a display couples tocomputer 162. The display is configured to show in real-time at leastone of a load magnitude applied to the external curved surface of thefirst shoulder prosthesis. In general, a force applied by the secondshoulder prosthesis to the first shoulder prosthesis is normal to theexternal curved surface of the first shoulder prosthesis. In oneembodiment, the plurality of load sensors are oriented such that thereaction forces are directed to a center or rotation.

Referring briefly to FIG. 22 a , display 164 coupled to computer 162 isconfigured to graphically display an external curved surface 384corresponding to the external curved surface of the upper housing.Computer 162 is configured to receive measurement data from measurementdevice 154. Computer 162 can perform calculations related to themeasurement data from the one or more sensors. Computer 162 furtherconvert the measurement data to a graphic form that allows a surgeon orsurgical team to rapidly assimilate measurement data. Display 164 iscoupled to computer 162 having a graphical user interface (GUI) 380. GUI380 is configured to provide an image of external curved surface 384 ofmeasurement device 154 and a rim surrounding the external curved surface384.

Display 164 is configured to graphically display a contact point 382 ofthe upper housing where the glenoid sphere couples to the externalcurved surface of the upper housing in real-time. In one embodiment,glenoid sphere 152 applies a force to measurement device 154 that isnormal to external curved surface 224. Furthermore, the display alsoshows a contact point on the external curved surface of the firstshoulder prosthesis. The contact point will move in real-time on thedisplay as the shoulder is moved through different range of motions. Inone embodiment, the display and computer is in the operating room toprovide the information in real-time to the surgical team. Othermeasurements that are made with shoulder joint system 160 are motion,position, joint stability, range of motion, or impingement to name but afew. Referring briefly to FIG. 22B, computer 162 is configured tocalculate when impingement occurs from the measurement data. In oneembodiment, display 164 notifies when impingement occurs by highlightinga rim 520 of the external curved surface of the upper housing. Rim 520highlights a portion of the rim where the impingement occurs orcorresponds to at a terminus of direction of the range of motion wherethe impingement occurs.

In one embodiment, one or more motion bars are displayed on display 164.The one or more motion bars are configured to graphically indicate arange of motion of the shoulder joint system as it is moved through apredetermined motion. Referring briefly to FIG. 23 , four motion bars(400, 402, 404, and 406) are disclosed each corresponding to a specificmotion. Each motion bar graphically illustrates a range of motionachieved in the installation of the shoulder joint system for thepredetermined motion. Each motion bar has a first end and a second end.The first end and the second end of a motion bar corresponds to amaximum internal rotation for a predetermined movement and a maximumexternal rotation for the predetermined movement. Between the first endand second end, the motion bar is configured to indicate an acceptableinternal range of motion and an acceptable external range of motion forthe predetermined movement. The motion bar is also configured toindicate a center of the predetermined movement. In one embodiment, abar indicates a position of the shoulder during the predeterminedmovement. For example, a bar 426 of motion bar 402 indicates a positionof the shoulder joint in an I/E rotation at 45 degrees adduction. A box428 on the display indicates loading applied to the external curvedsurface of measurement device over the predetermined movement via acolor map.

Referring briefly to FIG. 25 , a range of motion (ROM) overlay 390 onGUI 380 is disclosed. The motion data and load data from thepredetermined motions of FIG. 23 are stored in memory. In FIG. 25 , GUI380 graphically displays the movement of contact point 382 to theexternal curved surface 384 on GUI 380 for each of the four differentshoulder joint movement measured in FIG. 23 . A trace of a predeterminedmovement on the external curved surface of the measurement device asshown in FIG. 25 is a ROM overlay. GUI 380 is configured to provide atleast one ROM overlay on the image of the external curved surface of themeasurement device on the display of the computer. Stated differently aROM overlay comprises at least one load track corresponding to apredetermined movement of the shoulder joint. In one embodiment, theapplied loading can vary significantly at different points on the loadtrack. In one embodiment, the GUI 380 is configured to provide at leastone impingement ROM assessment that includes a trace that illustratesthe limits of abduction/adduction and horizontal flexion.

In one embodiment, GUI 380 is configured to provide an image of theexternal curved surface of the measurement device and a rim surroundingthe external curved surface. The portion of the rim is highlighted whenimpingement occurs and corresponds to the direction of movement of theshoulder joint. GUI 380 is configured to provide at least oneimpingement ROM assessment that includes a trace that illustrates thelimits of abduction/adduction and horizontal flexion.

Referring briefly to FIG. 3 , a shoulder system 160 is disclosed.Shoulder system 160 comprises a first prosthetic component and a secondprosthetic component. Shoulder system 160 is configured to transmitmeasurement data to a computer 162 and display measurement data on adisplay 164. The first prosthetic component and the second prostheticcomponent each have a curved surface configured to couple together tosupport shoulder system 160. The curved surfaces of the first and secondprosthetic component allow for a wide range of motion for the shoulderjoint. In one embodiment, the first prosthetic component is a humeralprosthesis 158 configured to couple to humerus 150. In one embodiment,the second prosthetic component is a glenoid sphere 152 configured tocouple to scapula 140. Humeral prosthesis 158 comprises a humeral tray156. A humeral liner or measurement device 154 is configured to coupleto humeral tray 156. Referring briefly to FIG. 36 , a measurement device1100 is disclosed. Measurement device 1100 compromises an upper housing1106, a bottom housing 1108, and a shim 1110. Measurement device 1100 ormeasurement device 154 is configured to couple to humeral tray 156 forproviding measurement data. Shim 1110 is a removable device to adjust aheight of measurement device 1100. For example, adding height canincrease the force applied to measurement device 1100 when placed in ajoint. Conversely, removing the shim or replacing the shim with athinner shim will reduce the force applied to measurement device 1100when placed in the joint. In one embodiment, shim 1110 couples to bottomhousing 1108 and retains measurement device 1100 to humeral tray 156.Upper housing 1106 has an external curved surface 1104 configured tocouple to another prosthetic component to support joint movement. Upperhousing 1106 couples to bottom housing 1108 to form a hermeticallysealed enclosure. The hermetically sealed enclosure houses at least onesensor and electronic circuitry configured to control a measurementprocess and transmit measurement data. In one embodiment, shim 1110 isconfigured to couple bottom housing 1108. In one embodiment, shim 1110is configured to couple measurement device 1100 to a humeral tray of ahumeral prosthesis. Although not shown, for measurement device 154, shim1110 is used to change the height of measurement device 154 to adjustthe load applied to the prosthetic component. In one embodiment,measurement device 1100 with shim 1110 couples to humeral tray 156 ofFIG. 3 . In one embodiment, a plurality of shims are provided where eachshim has a different height for adjusting a height of measurement device1100. Each shim of the plurality of shims is configured to couple tomeasurement device 1100. Furthermore, each shim is configured to coupleto a tray of the prosthetic component. In one embodiment, each shim ofthe plurality of shims includes one or more cutouts to retain a shim ofthe plurality of shims to the tray of the prosthetic component.

In general, everything disclosed for measurement device 154 herein abovealso applies to measurement device 1100. In other words, electroniccircuitry, sensors, or structures of measurement device 154 also applyto measurement device 1100. Although not shown the electronic circuitrydisclosed for measurement device 154 herein above is also withinmeasurement device 1100. Thus, figures related to measurement device 154will be disclosed when discussing structure, electronic circuitry, orsensors for measurement device 1100. Electronic circuitry 236 isdisclosed in FIG. 32 . Electronic circuitry 236 is placed within theenclosure formed by upper housing 1106 coupling to bottom housing 1108.Referring briefly to FIG. 19 a first sensor, a second sensor, and athird sensor are located within bottom housing 222 corresponding tobottom housing 1108. The first, second, and third sensors correspond tosensors 230. Referring to FIG. 5 , upper housing 220 corresponding toupper housing 1106 is shown prior to coupling to bottom housing 222.Coupling upper housing 220 to bottom housing 222 couples the first,second, and third sensors respectively to external curved surface 224corresponding to external curved surface 1104. More specifically, thefirst, second, and third sensors respectively couple to external curvedsurface 224 at a first predetermined radial location, a secondpredetermined radial location, and a third predetermined radial locationupper housing 220 when coupled to bottom housing 222. Referring brieflyto FIG. 28 , an illustration of sensors 530 and 532 are shown in across-sectional view illustrating radial locations. The third sensor(not shown) is spaced such that all three sensors are spacedequidistant. In other words, the first, second, and third predeterminedradial locations have an equal radius from the center of curvature. Inone embodiment, the first, second, and third radial locations of sensors530, 532, and 534 on external curved surface 224 has a greater radiusthan a radius of the external curved surface of the prosthetic componentthat couples to measurement device 154. In one embodiment, the first,second, and third sensors are located at or near the rim of the externalcurved surface. In one embodiment, the positions of the first, second,and third sensors have an equal radius relative to the external curvedsurface.

In general, measurement device 1100 couples to a first prostheticcomponent for generating measurement data related to a shoulder jointsystem. Measurement device 1100 of the first prosthetic componentcouples to an external curved surface of a second prosthetic componentas disclosed in FIGS. 1-3 . In one embodiment, the external curvedsurface of the second prosthetic component is configured to couple tothe external curved surface of upper housing 220 of the measurementdevice 154 only at the surfaces of the first, second, and thirdpredetermined radial locations corresponding respectively to thelocations of first, second, and third sensors underlying the externalcurved surface of the upper housing. A force applied by the secondshoulder prosthesis to the first shoulder prosthesis is directed thruthe first, second, and third sensors. As previously mentioned electroniccircuitry 236 couples to the first, second, and third sensors.Electronic circuitry 236 is configured to control a measurement processand transmit measurement data.

Referring briefly to FIG. 44 , measurement device 1100 is illustrateddisclosing different regions of external curved surface 1104 of upperhousing 1006. The regions disclosed herein also correspond tomeasurement device 154. A plurality of regions correspond to a locationof external curved surface 1104 where a force, pressure, or load ismeasured. In one embodiment, the plurality of regions correspond to afirst sensor, a second sensor, and a third sensor that underliesexternal curved surface 1104. Region 1172, region 1174, and region 1176correspond to the plurality of regions of external curved surface 1104and are located at a first, second, and third predetermined radiallocation. In one embodiment, regions 1172, 1174, and 1176 correspond tosurfaces of the first, second, and third predetermined radial locationsof the external curved surface 1104 of measurement device 1100. Regions1172, 1174, and 1176 are equal to or larger than the area of the first,second, or third sensors that underlie the radial locations. A firstregion of external curved surface 1104 relates to a circle 1196illustrated on FIG. 44 . In one embodiment, a first region is the areawithin circle 1196 of external curved surface 1104 of measurement device1100. The first region is illustrated as region 1192. In one embodiment,the surfaces of the first, second, and third predetermined radiallocations corresponding to regions 1172, 1174, and 1176 are above asurface of the first region (region 1192) of external curved surface1104 within circle 1196. A second region of external curved surface 1104of measurement device 1100 corresponds to a region outside circle 1196but does not include regions 1172, 1174, and 1176. The second region isillustrated as region 1190. The second region extends from circle 1196to rim 1102 of measurement device 1100 excluding regions 1172, 1174, and1176. In one embodiment, the surfaces of the first, second, and thirdpredetermined radial locations corresponding to regions 1172, 1174, and1176 are above a surface of the second region (region 1190). In oneembodiment, the surface of the second region of external curved surface1104 comprises an area that is above the surface of the first region ofexternal curved surface 1104. In one embodiment, rim 1102 of measurementdevice is 1100 is a maximum height of external curved surface 1104.Conversely, the first region corresponding to the area of the surfacewithin circle 1196 is the lowest portion of external curved surface 1104of measurement device 1100.

A method of measurement within a shoulder joint is provided hereinbelow. The steps disclosed can be practiced independently and in anyorder. The ordering of steps does not indicate an order or sequence butis merely to identify a step. In a first step, a first shoulderprosthesis is coupled to a second shoulder prosthesis. The firstshoulder prosthesis has an external curved surface configured to coupleto an external curved surface of the second shoulder prosthesis. In oneembodiment, the external curved surface of the first shoulder prosthesisis a measurement device configured to control a measurement process andtransmit measurement data to a computer. The computer includes a displayfor displaying the measurement data or to graphically displayinformation related to the measurement data. In a second step, a force,pressure, or load of the second shoulder prosthesis is directed througha surface of a first predetermined radial location, a surface of asecond predetermined radial location, and a surface of a thirdpredetermined radial location of the first shoulder prosthesis.Underlying the surface of the first predetermined radial location, thesurface of the second predetermined radial location, and the thirdradial location respectively is a first sensor, a second sensor, and athird sensor. In a third step, the first, second, and third sensors areplaced equidistant from one another at positions that maximize theradius of circle defined by the sensors. The first, second, and thirdsensors are oriented such that sensor reaction forces are directed to acenter of curvature of the external curved surface of the first shoulderprosthesis. In one embodiment, it is assumed that no frictional forcesor negligible frictional forces occur on the external curved surface ofthe first shoulder prosthesis or at a sensor interface. In oneembodiment, reaction force vectors are assumed to be normal to theexternal curved surface of the first shoulder prosthesis and thereforepass through the center of curvature of the external curved surface ofthe first shoulder prosthesis.

It should be noted that very little data exists on implanted orthopedicdevices. Most of the data is empirically obtained by analyzingorthopedic devices that have been used in a human subject or simulateduse. Wear patterns, material issues, and failure mechanisms are studied.Although, information can be garnered through this type of study it doesnot yield substantive data about the initial installation,post-operative use, and long term use from a measurement perspective.Just as each person is different, each device installation is differenthaving variations in initial loading, balance, and alignment. Havingmeasured data and using the data to install an orthopedic device willgreatly increase the consistency of the implant procedure therebyreducing rework and maximizing the life of the device. In at least oneexemplary embodiment, the measured data can be collected to a databasewhere it can be stored and analyzed. For example, once a relevant sampleof the measured data is collected, it can be used to define optimalinitial measured settings, geometries, and alignments for maximizing thelife and usability of an implanted orthopedic device.

The present invention is applicable to a wide range of medical andnonmedical applications including, but not limited to, frequencycompensation; control of, or alarms for, physical systems; or monitoringor measuring physical parameters of interest. The level of accuracy andrepeatability attainable in a highly compact measurement device orsurgical apparatus may be applicable to many medical applicationsmonitoring or measuring physiological parameters throughout the humanbody including, not limited to, bone density, movement, viscosity, andpressure of various fluids, localized temperature, etc. withapplications in the vascular, lymph, respiratory, digestive system,muscles, bones, and joints, other soft tissue areas, and interstitialfluids.

While the present invention has been described with reference toparticular embodiments, those skilled in the art will recognize thatmany changes may be made thereto without departing from the spirit andscope of the present invention. Each of these embodiments and obviousvariations thereof is contemplated as falling within the spirit andscope of the claimed invention, which is set forth in the claims. Whilethe subject matter of the invention is described with specific examplesof embodiments, the foregoing drawings and descriptions thereof depictonly typical embodiments of the subject matter and are not therefore tobe considered to be limiting of its scope, it is evident that manyalternatives and variations will be apparent to those skilled in theart. Thus, the description of the invention is merely descriptive innature and, thus, variations that do not depart from the gist of theinvention are intended to be within the scope of the embodiments of thepresent invention. Such variations are not to be regarded as a departurefrom the spirit and scope of the present invention.

While the present invention has been described with reference toembodiments, it is to be understood that the invention is not limited tothe disclosed embodiments. The scope of the following claims is to beaccorded the broadest interpretation so as to encompass allmodifications, equivalent structures and functions. For example, ifwords such as “orthogonal”, “perpendicular” are used the intendedmeaning is “substantially orthogonal” and “substantially perpendicular”respectively. Additionally although specific numbers may be quoted inthe claims, it is intended that a number close to the one stated is alsowithin the intended scope, i.e. any stated number (e.g., 90 degrees)should be interpreted to be “about” the value of the stated number(e.g., about 90 degrees).

As the claims hereinafter reflect, inventive aspects may lie in lessthan all features of a single foregoing disclosed embodiment. Thus, thehereinafter expressed claims are hereby expressly incorporated into thisDetailed Description of the Drawings, with each claim standing on itsown as a separate embodiment of an invention. Furthermore, while someembodiments described herein include some but not other featuresincluded in other embodiments, combinations of features of differentembodiments are meant to be within the scope of the invention, and formdifferent embodiments, as would be understood by those skilled in theart.

What is claimed is:
 1. A shoulder joint system comprising: a firstshoulder prosthesis comprising: an enclosure having an external curvedsurface wherein a plurality of sensors and electronic circuitry arehoused in the enclosure, wherein the plurality of sensors are located ata radial position relative to the external curved surface, and whereinthe electronic circuitry is operatively coupled to the plurality ofsensors to support a measurement process and transmit measurement data;and a flexible interconnect configured to couple the plurality ofsensors to the electronic circuitry, wherein the flexible interconnectcouples to a support structure coupled to an interior surface of theenclosure; a second shoulder prosthesis having an external curvedsurface configured to couple to the external curved surface of the firstshoulder prosthesis to support movement of the shoulder joint system; acomputer configured to receive the measurement data from the firstshoulder prosthesis: and a display coupled to the computer configured toshow in real-time at least one of a load magnitude applied to theexternal curved surface of the first shoulder prosthesis, a contactpoint on the curved surface of the first shoulder prosthesis, jointstability, range of motion, or impingement of the shoulder joint system.2. The shoulder joint system of claim 1 wherein the first shoulderprosthesis is a humeral prosthesis and wherein the second shoulderprosthesis is a glenoid sphere.
 3. The shoulder joint system of claim 2wherein a tray is configured to couple to the humeral prosthesis andwherein the enclosure or a humeral liner is configured to couple to thetray.
 4. The shoulder joint system of claim 1 wherein the first shoulderprosthesis is a glenoid prosthesis and wherein the second shoulderprosthesis is a humeral prosthesis.
 5. The shoulder joint system ofclaim 1 wherein a force from the second shoulder prosthesis is normal tothe external curved surface of the first shoulder prosthesis and whereinthe plurality of sensors are oriented such that reaction forces aredirected to a center of curvature.
 6. The shoulder joint system of claim1 wherein the enclosure comprises an upper housing coupled to a bottomhousing to form a hermetic seal and wherein the enclosure is sealed byan adhesive or an o-ring.
 7. The shoulder joint system of claim 1,wherein the flexible interconnect couples to a surface of the supportstructure at a predetermined angle such that the surface of the supportstructure is non-parallel to the interior surface of the bottom housing.8. The shoulder joint system of claim 7 wherein the plurality of sensorscomprises three sensors and wherein the support structure positions theplurality of three sensors to couple between the upper housing and thebottom housing.
 9. The shoulder joint system of claim 8 wherein eachsensor of the plurality of sensors underlies the external curved surfaceat predetermined locations and wherein each sensor of the plurality ofsensors respectively couples to a planar surface of the upper housingand a planar surface of the bottom housing.
 10. The shoulder jointsystem of claim 8 wherein the three sensors are spaced equidistant fromone another.
 11. A shoulder joint system comprising: a humeralprosthesis comprising: a stem; a neck coupled to the stem; a traycoupled to the neck: and a measurement device coupled to the traycomprising an enclosure having an external curved surface wherein theenclosure houses no more than three sensors configured to measureloading applied to the external curved surface of the enclosure, whereinthe measurement device is removable from the tray of the humeralprosthesis, and wherein the no more than three sensors are located atradial positions relative to the external curved surface; a glenoidsphere having an external curved surface configured to couple to theexternal curved surface of the measurement device to support movement ofthe shoulder joint system; a computer configured to receive themeasurement data from the measurement device; and a display coupled tothe computer configured to show in real-time: a load magnitude appliedto the external curved surface of the measurement device, a contactpoint on the curved surface of the measurement device, and at least oneof joint stability, range of motion, or impingement of the shoulderjoint system.
 12. The shoulder joint system of claim 11 furtherincluding: a position measurement system configured to measure positionand motion; and electronic circuitry coupled to the three sensors andthe position measurement system wherein the electronic circuitrycontrols a measurement process and transmits measurement data andwherein the three sensors are spaced equidistant from one another. 13.The shoulder joint system of claim 11 wherein a force from the glenoidsphere is normal to the external curved surface of the measurementdevice and wherein the three sensors are oriented such that reactionforces are directed to a center of curvature.
 14. The shoulder jointsystem of claim 11 wherein the three sensors couple to a flexibleinterconnect, wherein the flexible interconnect couples to a supportstructure at a predetermined angle to position the three sensors tocouple between the upper housing and the bottom housing at predeterminedlocations underlying the external curved surface, and wherein eachsensor couples between planar surfaces of the upper housing and thebottom housing.
 15. The shoulder joint system of claim 11 wherein theenclosure comprises an upper housing and a bottom housing and whereinone or more housing snaps couples the upper housing to the bottomhousing to pre-load the three sensors.
 16. A shoulder joint systemcomprising: a humeral prosthesis comprising: a measurement deviceincluding: an upper housing having an external curved surface; a bottomhousing wherein the upper housing couples to the bottom housing to forma hermetically sealed enclosure; and no more than three sensors, the nomore than three sensors including: a first sensor; a second sensor; anda third sensor wherein the first, second, third sensors couple to theexternal curved surface at predetermined radial positions; electroniccircuitry coupled to the first, second, and third sensors wherein theelectronic circuitry controls a measurement process and transmitsmeasurement data; a glenoid sphere having an external curved surfaceconfigured to couple to the external curved surface of the humeralprosthesis to support movement of the shoulder joint system wherein aforce from the glenoid sphere is normal to the external curved surfaceof the measurement device: a computer configured to receive measurementdata from the measurement device wherein the shoulder joint can be movedthrough a range of motion and wherein the computer is configured tocalculate a magnitude and a position of said force in real-time; adisplay coupled to the computer.
 17. The shoulder joint system of claim16 wherein the first, second, and third sensors are oriented such thatreaction forces are directed to a center of curvature.
 18. The shoulderjoint system of claim 16, wherein the computer is configured tocalculate where the glenoid sphere contacts the external curved surfaceof the upper housing in real-time as the shoulder joint is moved througha range of motion from the measurement data, wherein the display isconfigured to graphically display the external curved surface of theupper housing, and wherein the display is configured to graphicallydisplay a contact point where the glenoid sphere couples to the externalcurved surface of the upper housing in real-time.
 19. The shoulder jointsystem of claim 16 wherein the first, second, and third sensors arespaced equidistant.
 20. The shoulder joint system of claim 16 whereinthe computer is configured to calculate when impingement occurs from themeasurement data and notify the impingement on the display.